Using the M-16 kits is not worth it IMHO. The kits I have seen are rough, really rough. You can build a cheapie for under six bills easy. Oly cast lower-$100 or less, Parts kit(J&T, M1 sales, etc.)--$425 or less, there, you have a brand new rifle for $100 more than the crappy refinished kit gun.
The last gun I built turned out really nice for about $700. I used,
Bushmaster lower--$150
Colt A2 barrel(chrome lined, no bayo lug)--$130
J&T upper and small parts--$325
Wilson muzzle brake--$70
This turned out to be a great looking post-ban with no worn out or refinished parts.
Spend a little extra, the difference is huge.