I like the guy's name
gunbroker00 The other guy claims a "factory 4.1 inch barrel." I am pretty sure Colt never made one of those.
Pretty pricey stuff. Assuming gunbroker00 is being legit with respect to ATF, he is taking a Colt virgin lower and pairing with a Colt 6940 family upper. 10.3" or 11.5" 6945 and some other number. Nice if he can get that kind of money. There is a small group of sellers (I use the word purposely, as they are certainly not dealers, and they may not have FFLs either) who take stock guns, add some trim, do some Cerakoting, put it in a nice case, and get a boat load of money from otherwise mostly normal rifles on Gunbroker. You see this with Colt and KAC. There are a few names, that I will not mention. I am pretty sure one guy does this as a "hobby" and does not have an FFL.
But, back to gunbroker00, he is looking for what... $6k for that pistol? Even at high market prices for Colt pistol lowers and a Colt monolithic upper, costs are going to be $3k-ish, so to get that magic Colt pistol for $6k.
*** RARE *** <-- dead give away on GB and EE that someone is over-hyping.
To quote Joe Biden (who today was running for Senate in Ohio),
chicanery