This is a hell of a deal. You get the rifle plus $100 to deck it out with your choice of handguard, stock and BUIS. If you shop right you could easily configure your rifle for $600 give or take.
5.56mm NATO OEM Mid-Length 16" Rifle w/$200 Gift Card : AERO PRECISION OEM MID-LENGTH 16" RIFLE | Brownells
With the $100 you can get a Rear and Front Magpul BUIS and a CTR stock. Then all an Areo Keymod or M-Lok free floating handguard for $100.
Free Float Handguards | Aero Precision
That is a great rifle for about $650 shipped and transfered to depending on what you pay for transfers. This is a great rifle with some features that make it more appealing than guns like the S&W Sport II for a lot of people.