Well I definitely wouldn't buy it alone, unless it was only like 20$ or something. However I don't think it'd ever be bundled with a gamepad as the wiiu doesn't appear to support more than one per system... Hope I'm wrong.
The Wii U supports 2 Wii Gamepads at once (in addition to 4 Pro or Wii controllers).
However, the Gamepads are currently not sold separately as there are no games that support more the one pad. Particularly, none of the attractions of Nintendo Land seems to support 2 pads, so it wouldn't make sense to bundle it with an additional pad.
I personally think that Nintendo will wait for 6-18 months until they release separate Gamepads, and THEN they will bundle them with some new software that actually uses 2 Pads.