How much do you think?

I have these 18x9" boss 304's, chrome, brand new in the box......and i wanna do 20s, and im havin trouble selln them, when i bought them off ebay for 1000$....theres nothing wrong with them, perfect cond. but why cant i sell them???? heres the link to them http://www.tirerack.com/wheels/tech/offset.htm