I picked one up from buygunstuff.com. I think it was about $84 or so. If that's all you're ordering, by the time you add freight, it will cost as much as Brownells with a 10% off/free shipping coupon that's usually available.
I chose Pic rail, because I can add a little Pic rail section to any handguard or forend. Haven't had a chance to mess with it yet.