If i were you i'd try to get the Rock River Arms Tactical Operator 2 for $1k. I know your budget is $1k or below but trust me owning an AR is addictive and sky is the limit. So might as well get one of the best brands as possible. My first AR is DD and it was way more than my budget. Now i'm addicted and planning to get another one like RRA or Spike's.
But this is just my opinion.. don't take my word for it.