They're up on auction semi regularly, although less frequently lately. The last one i saw was being sold by Thanatos so he's probably the guy to talk to.
My guess is that, because the markup was dropping below +100 again, the few that craft them stopped putting them up on auction as much. I've seen it happen before until they came back up to ~+100.
If anyone is looking for one of these guns please look me up. I have more then a few for sale.