Why does the woman want to buy a dress?

M: Can I help you?
W: Yeah, I’m looking for a dress for myself.
M: Do you want something special?
W: Oh, just for a party. And I’d like either silk or cotton.
M: We don’t have silk. But this cotton one is very nice.
W: I like it very much. Any other sizes?
M: Yes, from size 7 to 10. What size do you want?
W: Size 9 exactly. How much is it?
M: It was $ 94 last week, but it’s on sale now you just pay $ 84 for it.
W: All right, and here is one hundred.
M: Thank you. Here is the change.