Edit: Paslode beat me to it.
After more searching I found out that I have a varriant of the Mil. Spec M4, made from Knight's Manufacturing Company (KMC).
Here is what I have in basic form, I think. Mine has a few more add ons, a titantium bolt & carrier and all that Jazz. So I guess it would be fair to say that this weapon was over/around 2k when new.
http://www.impactguns.com/store/KMC-98072.html