It is a standard AR 15 lower. Mine is a TI. RRA has complete guns as well. If you want a SBR you will need to Form 1 the lower and have it engraved. Orion Arms is the best place to go and get it done. $70
http://orion-arms.com/
There are some guys on this forum that may put an upper together for you.
Teppo Jutsu makes a great gun. It will take a while, but he is a hell of a guy and does top notch work. I am still awaiting my suppressor, but here is a vid of a form 1 suppressor jmorris did. I believe he posts hear.
http://s121.photobucket.com/albums/o...ent=m41kf1.flv