buy at
To purchase something for a particular price. I think we'll be able to buy these stocks at a better price if we wait a bit longer. My goal is to buy at 20 and sell at 25.
buy something at something
1. to purchase something at a particular place or at a particular type of sale, such as a store, an auction, a clearance sale, etc. I bought this table at an auction. This was bought at an auction.
2. to purchase something at a particular price or for a particular level of price. I bought shares in General Motors at forty and a half. The shares were bought at a good price.