there was a guy in the West here with one for sale about 6 years ago. Compete, it was 1/4 Mill. dollars.
As for handheld minis, no one seems to consider the weight, torque, and recoil. The guns, even in 5.56, are heavy, plus the batteries needed to operate the delinker and the gun, plus the ammo. The torque is significant, and tries to twist the gun off target - oops, there goes my first 2,000 rounds! Finally, the recoil comes as a push, not a shove. But it is a continuous push, as long as you hold the switch down.