I don't think the LE markings add much if any value to the carbine...they're not uncommon. I paid about $1200 new for mine about two years ago. Current asking prices seem to hover around the $1500 area or more depending on the seller.
If you can get that for $800...run...grab it and do not stop running until you get it home and be very careful about police with an arrest warrant for you for felony Colt acquisition at that price.
Post pics once you have it.