A Can I help you?
B I'm looking for shoes.
A What about these？
B Good.How much are they？
A twenty
B That's a little expensive. Can I get them cheaper
A 15yuan
B ok
可以这样设计对话：
Customer:How much is this?
Seller: 100RMB
Customer：Can you give me a discount?
Seller：Sorry, no discount, already the best price I can offer.
Because its color is so fresh, and much bigger than others in size. 100RMB is quite reasonable.