I know the availability of Non-LEO Colt 6721 AR15s is quite limited (134 examples, if I'm not mistaken).  Does anyone here have a feel for how frequently they trade hands?  I'm having a hard time evaluating what might be a fair price for a NIB example.

I would think somewhere in the $4500 range.  But, if it is in LNIB or NIB with box and paperwork the seller may be able to demand more. I would say this is more a collector rifle rather than a user. It boils down to what a potential buyer is willing to pay as there is a vey limited supply.  Make sure to verify status under 134 as I have seen 3 Tactical carbines offered for sale above the pre-ban cutoff but not marked as an LEO restricted weapon.  Prices ranged from $1500 for a very well used rifle to 2700 for a like new one.

GG, I concur w/Torakan.  They have been approaching the FA price range.  The SN must be BD000134 or below.  There were a couple in the Exchange forum a few months back.  Both were in the $4,000 - $4,500 range as I recall.  I do not remember if either were NIB.

Appreciate the feedback...

I'm facing the classic dilemma.  A NIB example is available for a VERY premium price.  On the one hand... I want the rifle and I know they don't come up for sale very often and I can probably swing the premium price.  On the other hand... I don't want to pay, say, a 50% premium over and above a "reasonable" price.  On the other hand (and I know I'm running out of hands here)... I know the pain of the "one that got away."  Most of us have probably suffered a few missed opportunities.

Perhaps I'll make the owner what I think is a reasonable counter offer and hope for the best.  Won't hurt to try.

I sold a NIB one for $5550 a few months ago.

Are you looking to shoot it, or save it?  If you are looking to shoot it, then don't bother with the higher price.  You can build one up for less.  If you have to have one of the special few, then be prepared to spend the cash.