Go Cheap- Go Russian

If you're a shooter, that is. You can buy a Mosin rifle for under $100 and pick up a tin of 440 rounds for under $100, shipping included. If you want to shoot for accuracy, a Soviet Mosin sniper rifle can be had for $800 or so for a real WW2 issue or half of that for a standard rifle with a period scope added.

Then you can buy match-grade ammunition for a quarter to a fifth of the price of match-grade .30-06. Of course it has corrosive primers and is Berdan-primed, but neither of those are show-stoppers.

Or you can get a 5.45x39mm upper for your EBR and buy that stuff, which can be had for less than $5 for a box of 25, cheaper than the slow-twist 5.56mm ammo.

(EBR = Evil Black Rifle, an AR-15 and clones)