I'd say PSA is the best at the <$800 range. You can get it real close to $700 with sales.
The biggest issue with assembling an AR isn't so much getting the parts together right - it's getting the right parts together.
US Army 1966-69, VFW Life Member, Retired Geek
The M&P is going to coast you. The M&P sport is the cheap one.
I have the Sport model and it was a steal at $650 (tax included) at the local sporting goods store. I've found them on the web for even less, as low as $550, but supplies don't seem to last too long from what I read on the various gun sites.
__________________ "... Americans... we want a safe home, to keep the money we make and shoot bad guys." -- Denny Crane