You can pick up the two included attachments, the slip scoop and deck, on the used market for roughly 3-4k total. So essentially they are asking ~16-17k for the tractor. Assuming that there aren't additional upgrades to the unit, ie added front hydraulics, 12V, 3 pt, etc, that price seems a bit high. In comparison, if you search online through the used dealer inventory you can find newer units with the same or less hours in that price range, possibly even cheaper if you can find a local deal through a private seller.
OP, what type of work did you want to do with the tractor? You can also look for older Ventrac 4100/4200 models as well as the Steiner 420/430 tractors. You can find them for quite a bit less $$$ and they are still great machines depending upon what you want to do with them.