$760 is a good price, actually.  Of course, I'd advise you to purchase just the lower via your FFL, and order the upper (in your desired configuration) directly from Bushmaster.  That way, you get exactly what you want.

Virtually all of the factory packages come with HBARs (heavy barrels).  These are cheaper to make, as they spend less time on the lathe, but they are also HEAVY, which goes against the whole purpose of the AR.  For a 20" AR, the 20" A2-profile barrel is tops.  Bushmaster only makes these with threaded muzzles, but you order the upper with no bayo lug and send it to Kurt's Kustom to install a post-ban-legal muzzle brake that looks similar to an A2 flash suppressor.  You'd have the closest post-ban-legal thing to an M16A2...

-Troy