Depending what state you're in and how large the gun shop is, $789.00 could be a pretty good price.
There will probably be guys posting about how you can save $25 or $50 by shopping around.
But then these are the same guys who will tell you that the way to fix a failure-to-feed is by "shooting a few hundred rounds through it" (which costs pretty significant $$$). Instead of telling you how to fix the problem by very slightly 'breaking' the too-sharp-cause-it's-brand-new edges on the feed ramp. Sigh.
In today's political climate, lots of shops have stopped carrying 'evil black rifles'. So I'd advise you to snap it up, and then you can begin the never-ending quest of buying as many 20 and 30 rd mags as you can find.
Have fun!
Navaho