One thing I would ask is if it was a commercial unit. Assuming it's an '01 (first year of the BX1800) then they averaged around 264 hours per year. That is a very high amount for the average homeowner, especially if it doesn't have a FEL. Being commercially used will be sort of a tradeoff; usually not owner operated, but usually serviced on time and professionally. Assuming it's in good condition, I'd say it's a good buy for the price.
Good luck!
Good luck!