
Cost
Fixed Price
When discussing cost as a verb, the price given is usually non-negotiable, as in a store price tag.
How much does this book cost?
Hypothetical Transactions
Use 'cost' to discuss the price of hypothetical or future purchases or actions.
Renting a larger apartment would cost more.
Past Purchases
For things already bought, use 'cost' to indicate the money spent in the past.
The wedding cost us a small fortune.