Cheap AR advice.
The cheapest way to buy an AR, without building, is to buy a complete lower, $300, a complete upper $400 with a bolt carrier group. You can probably beat those prices.
Now, a $700 AR built like this is worth about $700. Don't let a salesman tell you it would be crap or some web freak tell you it will be super. If it breaks, it is on you to repair.
Get a 5.56 chamber. 223 Rem reamers have no place in basic AR's.
Name rifles have warranties.
Stag, Spikes, Delton, Model 1 Sales are all good brands. Spikes would be about the best and Model 1 the cheapest.
Ideally, you would get an EOTech, but you are asking cheap. A $50 red dot is usable. . .sort of.
Buying a $100 scope, $10 rings will leave you needing $50 risers. If you normally fancy $50 - $100 scopes, this should work here.
Using this advice, you would have a fine range gun. It would be yours as bottom rung AR's don't have much of a following. When they do, people like a brand name and to pay $900.