If you're referring to Gunbroker, it's awful right now. I've watched 5 M4's be sold multiple times then the user "unregisters" I'm guessing when the buyer pays them. If it's too good to be true, it is.
someone in Pittsburg, Pa sold your gun twice yesterday... both times for $1400 and listed it again the same day but ended it before it sold again.. used your photos and even most of your description... you can see it under their "completed items" in their advanced search ... someone also sold my FDE M4 a few times not long ago.. ??? buyers beware !!!