Yeh i had something similar - i sold some stuff outside of ebay for £110, but for some retarded reason i didnt insure it. The guy said he didnt receive it, and paypal took the money off me (which like you i'd already wihdrawn so my account was negative).
Anyway, 3 weeks later the guy claimed the package finnaly arrived, so Paypal gave me my money back.
If your guy is a genuine eBayer with good feedback, this could be the same situation - he is unlikely to want to jeopardise his ebay account.
Good luck!!