Gunbroker.com Has Them But You May Pay More For It.
http://www.gunbroker.com/All/BI.aspx?Keywords=AR-15
I Just Got One Last Week. A Sig Sauer M400 Ar-15 .223/.556
THEY ARE OUT THERE, JUST DEPENDS ON HOW BAD YOU WANT ONE! HERES A PIC OF MINE RIGHT OUT OF THE BOX!