Could be a website glitch. Plenty of 'em available on Amazon, NewEgg, etc.Has the the FVS318G been discontinued? It doesn't seem to show up under of any of Netgear's "Product" pages. Searching for FVS318G on the Netgear site gives a hit for what seems to be the product page but that page doesn't seem to exist anymore. It was there 2-3 weeks ago. The link now just takes you to the Netgear home page.
If your router is fast enough for your Internet connection, adding a Gigabit switch is an easy and cheap way to go. There's no advantage to getting a router with Gigabit ports built in. In fact, for reliability, it's a good idea to keep the switch (and its heat) out of the router.
Gigabit traffic will flow port to port just fine on the switch.