One of the rollers has to be replaced on the deck, and some TLC. Looks like the same deck my Regent has, just a different width, mine is a 44". Some of the earlier Regents from the late 90"s early 2000's came with Briggs Vanguard engines I believe, can't tell from the picture of this tractor if it has a Vanguard. The Vanguard is a true commercial quality engine, for home use the tractor will wear out before the engine does.
Offer the guy $350-400. You can get parts for it on-line at Partstree.com. Much cheaper than the dealer on most parts. Good luck with your tractor quest.