I don't know anyone in the US breeding GN's. I love them as well and hated when I lost my first GN (4.5") due to it jumping. ExocticFinds.net does import them. You can also check any local fish clubs in your area for people selling them as well.
Beside PlanetCatfish.com, you can also go to PlecoFanatics.com. PF users are a little more active, IMO, and the site loads faster for me.