THEM: i would like 1 ball and 2 hats  YOU: you can have the ball but i need the books and the hats.  THEM: they are all equally worth low ammounts to me. i cant get less than 3 items  YOU: i'll take two hats and a book.  THEM: i cant sorry  YOU: ok. how about just the two hats and you owe me.  THEM: sounds good : )