New Stevie Drawing...

[skuncles]

It certainly looks like a copy to me. But as others have said, it's your money and you're free to do with it as you see fit. Seeing the two images on top of each other and seeing that they are identical seems to be enough proof that it's a copy. Most artists have their own unique touches here and there and this particular drawing has zero unique qualities to it.
But again, it's your money and if feel it's worth it, then go for it. Do be careful though. It's no different than people who will pay $40 for a CD copy of "Buckingham Nicks" because it's the "official Australian version". Or the Brazilian "Mirage" tour DVD. Neither of these have ever been officially released anywhere in the world, they are bootlegs, but if you want to pay good money for a fake item, go for it.

In your case, I would ask if you could stop in and see how your artist friend works. If he says no, or that it really wouldn't be possible for whatever reason. You should really reconsider the situation.