Go easy on 'em. Looking at all his posts, he has a large number of helpful or at least non-spammy posts too, and he's ultimately a valuable asset to your growing forum. He's probably just quite thrilled to be using your forum to get rid of his old paintball stuff because he doesn't do eBay or something.
Take it as a compliment that he is getting so into the classifieds section of your site.
Face it, it could be worse--he could be posting links to his auctions on eBay or his site.
Alas, if he is truly bugging your staff, and members, you could politely ask him to step it down a notch. Nothing severe has to be done.
Members will be members.
