How would you handle this?

[snapcult]

Selling prints are "art" is fine without a model release as long as you don't use the image to promote a product or service.

I would offer the guy one print at cost, since he was nice enough to pose for you.

 

[snapcult]

An 8x10 at Wal-mart will run you $2.50 - print one up, and give it to him for a signed model release.

If he'll go for it this is a good idea, then you can sell the image as stick and be protected in the future.