Ok they're not really "Mexican". These were Colt carbines produced for the Mexican government, and they have a Mexican roll mark. I guess the deal fell through. Maybe they were pissed about the wall that will never get built...
Magpul version here https://www.gundeals.com/colt-le6920-magpul-mexico-marked-5-56-nato, and the carry handle version for $699 here http://www.gunbroker.com/item/689273233
Also Colt also has a LE6920 rebate going for a free Drago bag and 30 round PMAG. https://coltrebates.pmcprograms.com/Submission/contact/3
Magpul version here https://www.gundeals.com/colt-le6920-magpul-mexico-marked-5-56-nato, and the carry handle version for $699 here http://www.gunbroker.com/item/689273233
Also Colt also has a LE6920 rebate going for a free Drago bag and 30 round PMAG. https://coltrebates.pmcprograms.com/Submission/contact/3