Walmart offers The Legend of Zelda: Wind Waker HD for Wii U for $15. Opt for in-store pickup to dodge the $5.99 shipping fee. (Amazon also offers this at the same price). That's a buck less than our mention from last November and the lowest price we could find by $5.
Update: The price has increased at Walmart; however, Amazon still offers it for $15 with free shipping for Prime members.