Not sure what area you're in, but one of the LFS in my area has 2 really nice green ones.
One is huge, easily over 12 inches, if I was to guess it has to be around 15- 16 inches when open, and about 10 when closed, the other is 8- 10 inches. Both are extremely healthy, they've had both for a very long time now. I think the only problem is that people get scared as soon as someone mentions that they can, and will eat your fish.
I know if you are willing to do the work in taking either of these guys out of the tank, they will give you a really good discount on them.
I know if they still have them when I finish converting my 220 to a reef tank, then I'm gonna have to buy one.
If you are interested in one let me know, I can get in touch with the LFS owner, I know they ship, and they take great care of their animals, or I can give you the info so that you may contact them directly.
....good luck in your search