Theres a couple listed on Craigslist right now, but honestly, you'll probably be best served just buying one new from RCA in Austin, when they run their sale:

http://sanantonio.craigslist.org/for/1482482152.html
http://sanantonio.craigslist.org/hsh/1490529488.html

...you could almost get a complete Nanotuners kit (tank, modified hood and all) for their asking prices.

-Corruption