The supposed listing is from Video Product Distributors (VDP), an American-based distribution company that supplies products to other retailers like Amazon and Newegg. According to the report, the site contains the following three listings for the Wii U.
WIIU SYSTEM – GM
WIIU SYSTEM W/ – GM
WIIU SYSTEM 349 W/ – GM
Aside from price, the listings do not describe what the differences are between the three different Wii U SKUs.
Even though the listing, price, and release date all seem reasonable, consider this to be a rumor. None of this information can currently be confirmed, and all of it could easily be faked. The best advise is to take this with a grain of salt until we get official confirmation from Nintendo.