I think your best bet is going to be contacting the seller and explain the situation. You don't have to mention that you wished to turn it into a hackintosh, a simple argument could be that the 1010 does not allow you to upgrade the RAM, while the 1011 you can upgrade to 2gb. Maybe they will exchange for a 1011 or refund you your money.
If that doesn't work you could pretty much take the loss, file a complaint, and leave them negative feedback over the issue. It sucks but only so much that ebay will do =\
It's not your fault they didn't list their product correctly and the seller is at fault in this situation. Hopefully they just do the right thing and work with you.