I have the GTX2 2000 (if I remember correctly) and LOVE it. With the modded fans, it's very quiet. The battery life when the power goes out is amazing, and I'm running tube amps and home theater equipment.
I can't speak of the going rates, but the Leibert UPS's are very solid units. You won't regret it.
Good luck on the sale Dubs.
Bob
p.s. I even have pics of the inside of my 2000, in case anybody wants to see them.