It is true that an AR build is never finished. I have had the "completed" rifle for a couple of months and am still looking for stuff to upgrade/accurize/make it better. I got a set of two-piece four-rail UTG handguards from the AR-15.com Equipment exchange for $40. Not a bad price considering everyone else is out of stock.
I still have to pick up the optics, I am all but committed to a NcStar MKIII 2-7 scope. The dealer that I am getting it through is throwing in a small double rail mount that goes on the scope for $6 bringing the total to $96 shipped. I don't know if a better deal exists out there. I just need to hurry up and buy the dang thing.
As far as ammo, I have about 600 rounds. I know I need more but with the crazies in California there is none to be found in the stores that is less than $.75 a round, I was having issues paying $.50 a round a few months ago. I am working on a reloading setup but that will take some time.