I was looking for one of those GG trials bikes 2 years ago. I ran into a similar challenging finding a good trials bike for a reasonable price. I found
www.searchtempest.com to be very useful. It allows you to do a larger area craigslist search in a perimeter around your zip code (or any other zip code).
The trialscentral.com forum is very helpful. Also check out
http://trialstrainingcenter.com/ and
Eventually, we found a 2006 Sherco 2.9 (pretty good copy of the non-Pro GG trials bikes) and got it for $2200. While we liked that Sherco, 6 months later we found a cheap 2002 TXT 280 Pro that needed a little work. In a side by side comparison we preferred the GG Pro over the Sherco. We just sold the Sherco this summer.
FYI I hear that the non-pro GG are bulletproof like some of the older GG enduro bikes. The GG Pro is ~10lbs lighter than the Sherco and Non-Pro GG bikes. The Pro seems to handle better. The GG Pro trials bikes are designed very well and appear to have a higher attention to detail than the enduro bikes. To shave the 10 lbs they trimmed out a bunch of metal and that makes the Pro more fragile than the non-Pro version.
Good luck with your search.