Again, I agree with the above, to build. A ton of options. If, you have access to a mill, you can go with an 80% lower (from Tactical Machining maybe) then have your own personal identification on the lower. Kinda neat. If not purchase a lower from any of a number of vendors. I have seen complete machined lowers for $79.00, but you have to go through an FFL, at least in California.
Buttstock, again a ton of options.
Upper, got wild of this one, too many calibers and options here to even start to list.
Bottom line is that you can build what YOU like and don't have to swap out parts later. Also, a big plus is you understand how everything goes together and if you should have a problem, maybe figure out what the issue is.
Make sure the dis-connect spring goes BIG end into the trigger or you can have BIG trouble. Just found that out from personal experience....
If you do have an issue putting it together, I guarantee someone here will have the answer!
Either way, you are going to LOVE this firearm. AR's are like potato chips, ya can't have just one....
Good luck!
hk404me