...although a nice design. For the price of a lower and registration requirements (the lower is a firearm), if one doesn't own one already, and then the upper, were talking way too much money. Such an item has market specificity - not for the general market.
I advise those looking for an airgun of such design to get a RAP4 M4 pellet rifle. It at least ejects shell casings and cost under 500 bucks. One of my worst airgun disposals - sold mine when I needed cash. Very fun plinker. Oh, and it was full auto and could be converted back to paintball or airsoft.
"Well, I thought it was a rabbit but it turned out to be Bear Grylls in a rabbit hide."