over the years I've had many many many black rifles....they are almost all the same....Stay away from Olympic
Don't spend any more than $1K....Academy of all places are selling Bushmaster M4's for $999 right now. However depending on the state you live in makes all the difference in the world...If your in Tx, Ar, LA you can get them pretty cheap.
Colt is just a name. Personally I have always liked DPMS. The AR lower recievers almost all come from the same Un named manufacturer. If you buy a minimum of 10,000 lowers, they will stamp whatever name you want..DPMS, Bushmaster, Stag..etc.
Some gun shops are raping customers....don't get rapped. PM me if you need some more info.