If you're looking at price (100 for the rails and 180 ball mount) they why not pay just 34 more dollars and get a B&W shipped to your door for $314 from this site
TandRTrailer.com :: Product Details
This is by far the cheapest price you will find for not only the B&W but any "hideaway" type GN hitch, Curt, and Reese also make a similar set ups, but requires you to cut a big square hole in the bed, and they're more expensive.
I ordered mine from TandR, they are great to deal with, got my hitch within 3 days, and of course this is the complete kit, comes with everything you need to mount it. I installed mine in about 3-4 hours, I took my time.
Also check out the B&W site, here is a link for the Turnover ball GN hitch.
B&W Custom Truck Beds, Inc.
On the left hand side of this page click on "Convert from a Hitch to a Level Bed in Seconds", this will give you a number of photos of the B&W installed(they are not direct links so I couldn't post them, sorry)
Also if you plan on running a fifth wheel in the future you can add on B&Ws companion hitch shown here.
B&W Custom Truck Beds, Inc.
Again on the left you will find links that give you photos of how easy the companion is to install on to the B&W GN hitch, it just simply mounts into you existing hitch, you can removed it and have a flat bed as well, I don't believe anyone else has a set up that allows for both and GN, and Fifth wheel and a flush bed but B&W does it all. By far B&W is a great product, you can't go wrong, I love mine and a lot of other people do too. Hope this helps.