$1300 gets you into the LMT Defender and Colt 6920 range. You can also assemble a complete BravoCo rifle for that and their gear is very very good.
LaRue Stealth uppers are $1200. You'd be over budget once you added a lower, but you'd have one of the most accurate mil-type AR uppers around.
If you pay $1,300 for an M4-style AR from DPMS or Bushmaster, you'll be getting ripped off.