Amazon offers Prime members the Nyko Wii U Power Stand in White for $5.73 with free shipping. (Non-members can spend $35 to qualify for free shipping; otherwise it adds $4.98.) That's the lowest total price we could find by $3. It utilizes the charging contact points and the AC adapter of the GamePad.
Note: Amazon also offers it in Black for $9.97 with free shipping for Prime members. That's the lowest total price we could find in that color by $3.
This item will not arrive before Christmas.