You say, “How much do you want to sell your phone for?” Examples: I bought the phone for six dollars. I paid six dollars for the phone. For.

How much are you asking for your phone? How much do you want for your phone? What do you want for your phone? How much are you selling your phone for? What’s the price of your phone? “At” can be used for prices. I bought Apple at $10. (Stocks) At $150 per pair, I can’t believe anyone buys those Nikes. I pay half that for mine. ( You are talking about a pricing level that varies, or a decision that is based on a certain value)

How much do you want to sell your phone *for*? How much would you like to obtain/receive for your phone? What is the price on your phone? What is the price-tag on your phone? How much are you selling your phone for? How much for your phone? Are you selling your phone? How much?!