Are you interested in fancy logo's or just something to shoot with? If you don't care about logo's or pictures I recommend Anderson or Palmetto State Armory. Both are easily found around $50 online.
My best piece of advise would be stick to companies with a known reputation and who advertise as building within mil-spec.
I have built AR's with Anderson, PSA, RRA, Spikes, CMMG, DPMS stripped lowers and every single one of them was as good and reliable as the others.
I would also recommend PSA's BCG. They are running them on sale until tomorrow for $79.99 and the NiB coated ones for $99.99. Both are excellent.