i bought the refurb wii u from nintendo 2 months ago and got a brand new unit, its of course ymmv whether the units they are sending out now are still new or not. up until E3 wii u's were languishing in sales so they had a huge overstock, but they have been doing pretty brisk sales since MK8 and the E3 announcements.
Remember that you can buy 3-4 copies of MK8 at Target this week for $46/copy ($15 preorder promo deal) or even $35 if you get them to PM amazon. You can redeem the Club nintendo codes from those MK8s for a free copy of Pikmin 3, Super Mario U, Zelda HD, and Wii Party U. Then trade in the extra copies at Gamestop or Best Buy for $30-40. Take that trade in money and buy a Pro controller, Motion+ (both on sale at Best Buy this week), and anything else you want.
Also the refurb Wii U's all count as DDP, so for every free game you redeem you get back $4-5 in DDP eshop cash, and can use that to buy Luigi U. A friend did that this week, bought the refurb Wii U for $225 shipped (tax), bought 4 copies of MK8 at Target, traded 3 of them back to Best Buy for more than he paid and bought accessories. For around $320 he got 6 games, 2 pro controllers, 2 motion controllers, and leftover $20 in eshop credit. hard to beat
time is ticking down though you only have until 7/31 to redeem the MK8 CN codes and claim your free games. you don't need a Wii U to do that part, you get eShop codes and have until 8/30 or 9/30 I believe to redeem them.