I bought a Gravely Z152 last year on repo. Was $7,000 something new, I bought it with 100 Hrs. and it cost me $3,000. I love that machine, and I've used them all (Scag, Honda commercial, Bunton, Exmark etc). This mower is the bomb, and built like a tank. Look on Flea-bay for low hour repossession units, they are out there.
Here is a link to my mower:
http://www.gravely.com/Commercial/Zeroturn/100i/152imxdz/Pages/features.aspx
Good luck in your search.