$800 Rifle in .223

[NyleRN]

You've already got a PSA build. Your next step is a White Oak with a matched BCG

Or a Rainier Arms match barrel

 

[HamYankee]

I would advise buying a complete rifle on sale. Get a good deal and get your feet wet.
Whether you buy a complete rifle, or build, you'll probably swap out parts anyway and it will be a work i progress.
My two cents.

 

[BehindBlueI's]

You've already got a PSA build. Your next step is a White Oak with a matched BCG

The one I've got is for a patrol rifle. It's done. For anything else I'll start from scratch. Maybe another PSA.

 

[PGRChaplain]

Watch Grab a Gun. A couple weeks they had Colt, magpul model in Black or FDE for $849.00.

 

[Otis812]

A good cheap starter AR? GunBuyer sells the Smith & Wesson M&P 15 Sport for $529.00. They don't have forward assist or dust cover but a good price for an entry level AR to beat around. You just have to watch when they get their stock in. I've got a PSA but picked one of these up just because of the price.