I would recommend getting a Wii U, but the actual Zelda game isn't coming out for a LONG time, and the Wii U will probably be cheaper once the game is close to coming out. So it would be logical to wait until then to get a Wii U.
Ebay can save you a lot of money on cosplay stuff. I'd personally say go for the Wii U and, eventually, Zelda U (Maybe WW HD first). Make sure to check ebay first though to see if your materials are there or not.