There was a grower who had several plants available on ebay last fall, but I haven't seen any available there since. I've taken to purchasing seeds lately. They just arrived this week, so we'll see how that goes. I figure it's a good, cheap experiment.
As others have mentioned, they can be very tempermental. I have experience with G. flexuosa x lobata, G. pygmaea and G. violacea. I'm pretty sure the G. pygmaea was DOA, it never did much of anything and just perished. The G. violacea is still around, but grows in fits and spurts. Sometimes it looks like it's on death's door, but then it seems to come back. I've tried growing it under several different conditions and it seems to like my highland terrarium the best. It hasn't flowered for me yet. The G. flexuosa x lobata just grew like crazy and started flowering as soon as it entered my collection. It did great until my 3 year old decided to "pick the pretty flower for daddy" and pulled the entire plant out of its container. It never recovered.