Check out this price list from this web site. This came to our department in a LEO Equipment periodical. Don't have any idea of how the price compares but the add showed alot of stuff for the price....All this for only $399.00
It included a QD lower handguard available in camo covers, triple lug clamping bar with dovetail interface, multi-position sling swivel, selective multi-position MIL-STD rails with spring loaded screws, SIR top combination handguard sleeve available as a drop on full lenghth perfect C-model or M-model with delta ring required, dual interface rail, removable dual rail support
http://www.armsmounts.com/list.html#45This was copied from the site:
4 Members Of The S.I.R. Family.
A.R.M.S. Item #59M Full Length Rifle Bi-Level S.I.R. Sugg. Rtl. $399.00
A.R.M.S. Item #58M Midlength Bi-Level AR15 S.I.R. Sugg. Rtl. $399.00
A.R.M.S. Item #45M M-4 Carbine S.I.R. Sugg. Rtl. $399.00
A.R.M.S. Item #51C A2 Carry Handle Carbine S.I.R. Sugg. Rtl. $369.00