Welcome! Stop by the http://www.firearmstalk.com/forums/f2/
section an tell us a little bit about yourself, so we kinda know who we're talking to.
As for your question, there are countless
options that would satisfy what you're looking for. Shop Shooting Supplies | Reloading | Gunsmithing | Hunting gear — MidwayUSA
is one of the bigger places for a variety of AR stuff. Searching through their catalog will educate you very well
in regards to what is out there, then start directing your ordering to whoever has the closest sale. If you ever start building AR/M4gery types feel free to PM me for more links and there are MANY
others here (one of whom really got me going) that are more
than willing to help.