Well, just for a laugh, after reading along the lines of the people that have grown wise to the now well-known so-called "419 frauds" (ie. those predominantly Nigerian email scams that tell you that your long lost relative has left you ?25million, lol). Tell the guy that you think "OK, the Moneygram thing is cool", and that you will do the deal!.....
... But only on one condition!
In that he should take a clear photo of himself with his virus standing outside the "restaurant" in question (fully in view) in order to verify his authenticity.
Say you wont do the deal otherwise, but say you DO have the money immediately "ready" to send via Moneygram after he complies, and that you're extremely eager to get your hands on the Virus.
See where that gets ya. If he tries to squirm out of it, just re-iterate the "need to see the simple described photo as proof, or otherwise the deal is off", and issue it as an ultimatum.
Might give us more time to think something up, while putting the ball in his court.
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Or, you could insist that you send him a snail-mail letter via post, to his home address, and get him to scan or photograph the letter once he's received it to show you and therefore authenticate his address.... You might then be able to set something up, or nail the bastard somehow, once you know it.
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Otherwise, just send him an email with a nice executable "virus", and tell him that the file contains your personal details, or something.....
Sorry I can't think of anything more original.
Damn well worth a shot, though.
.... Remember you're not the first and most probably not the last he's going to try it on. The next 'buyer' that is preyed on might not be so lucky.