Yes，we will ask like that too.
The simplest way is to take what you want to the shop assistant and ask " How much is this" ------- 这个多少钱？or 这个怎么卖？if you are not so sure about the measurements.
By the way, that was a nice worksheet. :) But please notice that PEACH is 桃 and BUTTER is 黄油. We say CAN in Chinese as 罐儿 （guanr 4） more than 听。