I was in your place a couple years back, now I've bought a complete, and completed a partial build. Other than having shot quite a few I knew very little. Bushmaster, Colt, Bravo Company, Rock River Arms, Smith and Wesson, would be a few of the complete builds I'd check out. You'll find some DPMS, Delton kits for cheaper, but I've heard mixed results. I'd personally recommend building a lower receiver, since it can be completed relatively easily and with tools most of us have, and buying a complete headspaced upper. Or just buying a decent complete on sale. I got my Shrubmaster for less than 900. Just my opinion, expect many.
Always good advice, and you get to shoot.