I just sold one the other day, but I do have this one that I now think I'm going to sell. I was going to use it as a secondary regulator to force carb and push soda but it has right hand threads and the primary that I use has left hand threads and I didn't want to mess around with it to make it work. As you can see it doesn't have a high pressure gauge but I know they are pretty cheap. It's a Cornelius brand and the label say "Secondary Regulator Maximum Inlet Pressure 200 PSI." So I'm sure it can also work as a primary.
I'm not sure what it may be worth so if you're interested make an offer.......