答案：D

本题考查与价钱连用的介词的用法。value在本句中是动词，“估价”，后常用value +名词+at+具体多少钱，表示“估计某物值（多少钱）”，此时at表示价格、数量、速度等；后面“花（多少钱）买下某物”，既可用buy sth. at，也可用buy sth. for。思路拓展:

①for表示交换的概念，如：I gave him a record for his stamp.

How much did you pay for the bag?

I bought this set of coffee cups for $ 20.

②常用at a high/low price来表示“以高/低价”。