.223/556 ammo is scarce and the stuff that's worth shooting isn't cheap anymore, probably won't be until things settle down in the middle east a bit.

FWIW, I bought an AR-15 a few years ago because it was much cheaper to shoot than my M1 for highpower competition. I just recently bought a .22 target rifle to practice with because .223 is getting too expensive to shot regularly. I've heard of a lot of folks spending $500 or so on .22LR uppers for plinking and marksmanship practice because right now it would pay for itself in just a few thousand rounds.