I would say buy, but you have to have patience.. And that is if you can live with ban era Colt "issues" like sear block, etc. Those don't bother me, so..
Last few months, there have been a few ban and preban era "A2"s LE trades on gunbroker for as low as $650... Some have even been ban era LEO rifles with a M16A2 barrel with bayonet lug. As opposed to the Sporters with no bayonet lug. Sure, they are used but that just means you don't have to worry about scratches, etc.
With a Colt, you get known quality, "correct" color parts, etc..
Of course, I am a Colt snob from 20 years of service. Almost Everytime that I have tried a clone, something disappoints me. It's the little things like finish, mushy selector, minor parts differences, etc. Same reasons I don't do AK builds.