That's the odd thing, I've never seen them in the Marketplace, and never on the auction house. Crim has never asked for one either (if I'm at the computer I hit Crim once an hour). I sort of wonder if they aren't really in game yet, and will be in the Adventure area that isn't released yet.

And yeah, after having four white ferrets, I'm really attached to white weaselbeasts. :D