Well...all was good until you mentioned the "machinegun" and that left a lot of us on the fence. First off you'd need a class-lll license to legally purchase a full auto weapon and if you aint a gun dealer your odds of having one are pretty low. And if you were into firearms that much, to have a class-lll, you probably wouldnt have to ask using the "machinegun" generalization. So now we are left with the feeling you are mocking law abiding gun owners like the rest of us are.
Had you asked normally I'd probably say buy a Garand in order to own a piece of history as well as a fine plinker.
And again, Rich shows how full of poop he is.
It's not a class 3 license, but a class 3 tax. 50 or 60 bucks per Machinegun. If you're clean enough for the Air Force Academy (IIRC), you're probably clean enough to pass the background check. Unfortunately, the supply of MG's is so controlled that their prices range from 5 grand to 20 grand, even for the most commonly produced machine guns of the world.
If that price isn't restrictive to you, neither would the price of ammo be. With the dwindling supply of surplus ammo from the cold war, you'd most likely be burning up at least 12 dollars every time you "Rock and Roll."
As for the Bushmaster and AR30? I'm not too familiar, but that seems awfully expensive. The Garand's price tag is about right. It should be a nice one for 800-1000.
As for a sniper rifle? It's a roadkill scare tactic assertion that you're actually going to get a sniper rifle. You'll be looking at a hunting rifle. If you really want to "Feel" like a sniper, look for a synthetic stock. For the Model 70 / Rem 700, you're looking at 500-800 for pretty much all calibers.