代价(dài jià) - price, cost in Mandarin

代价 (dài jià) is price in the sense of what something cost you: the sacrifice, the damage, what you gave up. It lives with two verbs above all, 付出代价 to pay a price and 以...为代价 at the cost of, and it takes weight adjectives rather than number ones, so 很大的代价 or 沉重的代价.

Never use it in a shop. The number on the label is 价钱 in speech and 价格 in writing, and asking 这个的代价是多少 will get you a puzzled look, because you have just asked what this thing cost someone in suffering. English lets price cover both jobs; Mandarin splits them cleanly.

It is also almost always negative or at least sobering. Even 成功的代价 carries the implication that something was lost along the way. If you want the neutral idea of what a plan will cost in time or money, 成本 is the word, and it is the one that turns up in business Mandarin.