Have you even talked to this guy to try and work something out...or is this site the first place you came to bitch? Either way, I say lesson learned for the future so you don't get yourself in a predicament like this again. However, I know the majority of folks here are stand up guys that would at least attempt to make this right. In the end, you were mislead, but can only blame yourself. You need to look out for #1 to cover your own ass regardless of how trusting you want to be of people. If you were intentionally mislead, good luck getting anything back, if not, you may stand a chance.
That being said, the seller doesn't have to do anything, but I believe it would be the right thing to do.