The cost of a card or Event is the amount that must be paid in order to buy it. A card's cost is indicated in its lower left corner, and an Event's cost is indicated in its upper left corner. Usually this is some number of coins, symbolized . In order to be able to buy something, you must have generated at least the requisite number of and earlier in the turn (and not yet spent them on other cards or Events). The principal way of generating is by playing Action and Treasure cards; Coin tokens and the Event Borrow provide alternative ways of accumulating .
 Other symbols in costs
The costs of some cards from Alchemy include a Potion, symbolized , in addition to some number of (possibly 0). The and components of costs are orthogonal; in order to buy a card with in the cost, you must have played a Potion card in addition to sufficient Actions, Treasures, etc. to produce the requisite number of .
An asterisk (e.g., Supply have asterisks in their costs to remind players that, despite having a cost, they cannot be bought. Peddler has an asterisk in its cost to remind players it has an effect which changes its cost.) indicates a card's cost is not what it seems. Cards belonging to piles not in the
Asterisk and plus signs are only reminders; unless otherwise specified, a card still has its normal cost for all purposes described below.
Some cards in Empires include Debt in their cost, symbolized . This means that part or all of the cost of the card can be paid for in at a later time. While is used to pay off , the costs on the cards themselves are orthogonal; a cost in is neither more nor less than a cost in , for the purposes of effects that care about costs.
 Other functions of costs
Costs can serve other functions in gameplay, outside of their role in buying something. For example, most gainers and several trashing attacks can only gain or trash cards of specified costs; most trash-for-benefit cards have effects that depend on the cost of the trashed card; a card's cost determines whether it is eligible to serve as the Bane for Young Witch, be imitated by Band of Misfits or Overlord, or be set aside by Prince, Inheritance or Summon. For this reason, all cards have costs, even those that it is never possible to buy, such as Shelters and Prizes.
 Changes in cost
Some cards have effects that temporarily reduce the cost of some or all cards: Bridge, Quarry, Peddler, Highway, Bridge Troll, and Princess, as well as the Event Ferry. When these effects occur, costs are changed for all purposes—not only the cost of buying cards is changed, but so are other effects that depend on cost such as those listed above. These abilities change the costs of cards, but not of Events.
In general, more "powerful" cards and Events have higher costs, but overall power is not the only consideration that goes into determining cost. For example, Chapel is often cited as a card whose strength is considered disproportionate to its low cost of . Costs between and especially are influenced by how useful a card is as an opening, and how desirable or necessary it is to be able to accumulate multiple copies of a card with extra +Buy. Cards with beneficial on-gain or on-buy effects typically cost more than their on-play effect would seem to require. There are also instances where cards have a different cost than their power level might suggest in order to interact better with other cards: Rats costs to interact favorably with trash-for-benefit cards, while Border Village costs to give you a wider range of other cards to gain with its when-gain ability.
In general a card will never be strictly better than a similar card with the same or a higher cost.
Most Kingdom cards cost between and ; there are only eight piles with cards costing more than (as well as three Events) and one card costing less than (as well as five Events). This means that, in most games of Dominion, there is a gap in the supply at the costs of and . This gap can influence gameplay in subtle but substantial ways: for instance, it means that Upgrade can be used to trash Copper without gaining anything, but cannot be used to gain Province. In the rare games when - or -cost cards are in the Supply, therefore, the utility of a card like Upgrade can change dramatically.
 0 cost
Cards that cost Copper, Curse, Ruins), or are non-Supply cards that are meant to be quite powerful. In the latter case, a null cost helps indicate that these are not normal cards, and discourages any other use for them than playing them (such as remodeling them).are either meant to be so terrible that they're essentially free (
Events that costare meant to be always available, and come with some penalty or restriction to prevent their abuse.
 1 cost
Save, the only Event that costs , has a relatively minor effect that is intended to be almost always available.
 2 cost
+Buys. This includes cards whose effects are usually relatively weak or inconsequential (such as Pearl Diver or Duchess); cards that can be strong, but only if you can accumulate many copies of them, so the low cost is necessary to make that possible (such as Fool's Gold or Native Village); and cards that are strong individually but offer diminishing returns for accumulating extra copies, so it doesn't overbalance the game too much to be able to buy up many of them (such as Courtyard or Hamlet). The most extreme example of this last class is Chapel: it's often described as the strongest card in the game relative to its cost, but rarely does anyone need more than one copy of it; therefore the fact that additional copies are easy to get has little effect on gameplay.is the lowest normal cost for Kingdom cards; they are priced so that players can always open with them, and can easily pick up extra copies of them with spare
TheEvents mostly give +Buy and a small but useful bonus, offering another use for extra the player may have in their Buy phase.
 3 cost
Cards and Events that cost Silver.are priced so that players can open with two of them, but cannot, in general, open with one of them and a card costing . They are typically more powerful than cards and Events. Cards and Events at this price point also directly compete with
 4 cost
 5 cost
 6 cost
Cards and Events that cost Gold, and as such tend to be exceptionally powerful; so much so that, in general, players may not open with them.directly compete with
 7 cost
Cards and Events that cost King's Court, perhaps the most powerful card in the game, is at this price point.still compete with Gold, but the extra in cost means these few cards and Events are just that much harder to acquire. Cards at this price point can be seen as a consolation prize for not making , but also interact nicely with remodelers with an "exactly more than" specification on the card they gain, allowing them to move smoothly from Gold to Province.
 8 cost
Cards and Events that cost Province, and thus have to be worth giving up a Province buy to acquire. Peddler, while nominally costing , is more often paid for by playing Actions, often picked up with extra buys at . By coincidence, until the release of Empires, all cards and Events that cost had names starting with the letter "P".directly compete with
 9+ cost
Platinum, at , and Colony, at , have the most expensive cost of cards in the game, and Dominate, at , is the most expensive Event in the game. The two most expensive Castles also fall into this price range, and all the cards and Events in this category can be extremely powerful. Their high cost usually leads to games including them lasting longer than usual as players build their decks up to field enough to buy them.
 Potion cost
Since the only way to buy a card with Potion card, such cards are generally more inconvenient to acquire than comparable cards with costs. To motivate the player to go to the trouble, such cards are typically fairly powerful and reward accumulating multiple copies of them.in the cost is the relatively inflexible
 Debt cost
Debt allows players to pay some or all of a card or Event's cost at a later time. Cards and Events with solely in their cost can be bought at any time, provided the player does not already have . Thus, while they may be expensive, they can be bought on a player's opening turns, though this may mean that they can't buy anything else for the next turn or turns. As such, cards and Events with no other cost tend to have some feature or penalty that makes them not worth buying in the first few turns.
One card (Fortune) and one Event (Wedding) have both a cost and a cost; the same concepts from the purely -costing cards and Events apply, but now these two have an additional threshold that must be met as well, rather than being able to buy them at any time. At , Fortune is the most expensive object in the game, though since only half of that cost has to be paid up front, it is easier to access than Platinum, Colony, and Dominate.