Tom walks into a shop. It has a sign outside: " Second hand clothes bought and sold ." He is carrying an old pair of trousers and asks the owner of the shop. " How much will you give me for these?" The man looks at them and then says, " Two dollars." " What!" says Tom, " I think they are worth  at least five." "No," says the man, "They aren't worth a cent  more than two dollars." " Well," says Tom. Taking two dollars out of his pocket, " Here's your money. These trousers are hanging   outside your shop. The list price of them is six dollars and a half. But I think that is too much money, so I want to find out how much they are really worth." Before the shop owner can think of anything, Tom walks out of the shop with the pair of trousers. The shop owner insists  that the trousers are worth only two dollars because   _  .
he wants to sell them cheaply he wants to buy them cheaply he doesn't like the trousers they are old and dirty