Re: wanting a ar best buy or build?
I prefer DTI over all of them, equal to the better names, and Kits are typically in the $460 range (fixed stock Carbine A2) or $530 (M4 with a 7 twist lined barrel) the more you option it up the more it cost.
Here in GA DIT stripped lowers go for $100, so for about $650 you can a nice M4. and the 7 twist will handle any ammo you throw at it, not just the 55, 62 & 69 gr stuff.
Del-Ton (DTI), Spikes, Bravo Co. (BCM), Noveske (if you have the $$$)