you guys are missing the point..he's selling the "business" patent, the idea, everything, and working product, for 250,000 dollars which is an extremely high evaluation. I would ask the guy what his sales are so far, if any and see what he's selling them for retail and then wholesale, then see what his profits are then make an offer from there if i was serious. but his eval is really high.
fully lic. and ins. 10yrs exp.