Lots of good choices in this thread. You can get a great AR for under $1g that meets you needs with 223 ammo and mags being rather cheap.
My 2ยข, I like rifles that are capable of MOA or sub-MOA accuracy. I haven't seen any (but am sure there are) AKs or Mini-14's/30's that can group that tight. There are a lot of AR's and M1A's that can.