Save your pennies or get a loan. Ronnie Barrett will only sell a factory built rifle, not parts kits or receivers (at least to the gun-owning public). Been there done that, so I scoured GunsAmerica until I found one I could afford.
After owning the M82A1 for over 3 years now, I can see why Barrett is skiddish about "parting out" their weapon. There is the possibility that someone could partially build an M82, and if one part is left out/off (such as the muzzle brake) there is a definite chance for disability if one should fire the thing without it being completely built. For some, human nature and a lack of patience can and probably would take over..."I can't wait to try this thing out, I don't need
every recoil spring..."
The result would certainly be some lawsuit against Barrett, ("Barrett knowingly produced a product that was too dangerous for the general public to build", etc, etc, etc...). So, as much as I know you probably wouldn't shoot the thing until
every part was in place, you & I know the types who wouldn't wait. I'd have probably been tempted myself, to be honest.
The 50BMG is nothing to trifle with. It is one friggin' powerful cartridge, and a lot of thought and engineering went into the 82A1 to make it safe to shoot as a stand-alone semi auto rifle as opposed to having to own an 80# Ma in a pintle. One can only get a real understanding of what you're dealing with when you chamber something designed to shoot a half-inch 650+ grain bullet at better than 2500 fps. Pulling the trigger the first time is a bit hairy. Cleaning the heavy chunks of steel that make up the bolt/barrel and other assemblies really give you an appreciation for what it takes to tame the beast of a detonation that happens within its chamber. Awesome doesn't even come close.
As I said, save the pennies and buy the whole enchilada. It's worth every hard cent.