The cheapest is the Hess, now called Vulcan, at around $1200. Its cheap for a reason, sort of like a Lorcin. The best value for the money is the BFG50 by Mark Serbu at around $2200. There are about 10 companies making 50BMG uppers for AR15s now and they all run under $2000. Ferret, Safety Harbor, and Watsons are well respected in the Upper catagory.