Valkyrie Arms is not producing their M3 gun at this time, but may do so in the future.
http://www.valkyriearms.com/
Note that due to Federal laws and the BATF, the Valkyrie M3 is quite different than a full auto M3.
Unlike the stamped metal receiver M3 it has an upper and lower receiver design made of milled steel, not stamped.
They made a sliding stock version with a 16" barrel, which looked really weird, and a pistol version with a stock welded closed that looked more like a real M3.