I have a Bushmaster Varmint Special that I use for prairie dog hunting and long range target practice. I'd rather not use it when my friends and I go plinking, so I was thinking of either building another AR or getting another upper for my bushy. What do you guys think? It would be mainly for shooting lots of surplus ammo and never required to be terribly accurate. I've never used iron sights on an AR, but I think I could handle it, so I don't care if it's a flattop or A2 upper.

Both ADCO firearms and J&T have quality offerings at good prices but don't forget the Equip exchange here on AR15.com

I have a J&T A2 Carbine upper (from their kit), 16" barrel by Shaw, that I am perfectly happy with.  I also have a 16" flattop upper from DPMS that also is very good.  Both function well, and have not malfunctioned in any way since new.  These are my most recent purchases, and I am happy with them and would buy from either company again.

Go to ADCO firearms.  They offer the best deal for an excellent upper.  DCM
Rock River upper for 555 plus 4 for shipping.  That is the best deal I could find I looked everywhere and ended up going with them.  They are very fast and the upper is perfect and new.  I am usign it for accross the course shooting.
It only took 3 days to get it.  Plus Steve is very helpful.

Good luck and aim straight.