set a/the/(one's) price (for something)
To establish or come up with a price for which one is willing to buy or sell something. A: "How much do you want for this old typewriter?" B: "Set a price, and I'll see if it's fair." He decided to let everyone set their own prices for the artwork according to their own budgets, trusting that people wouldn't rip him off. The place sets the prices way too high for this stuff. There's a shop in town that sells most of for much cheaper!
set one's (own) price
to name the (relatively high) price at which one is willing to sell something. If you have a first edition of Milton, you can almost set your own price. They are in great demand by collectors.