It appears Amazon UK has dropped their Mario Kart 8 Wii U bundle price to £209.00. Sources say the old price was approximately ~£229.00.
This is a pretty decent price considering the Super Mario U + Luigi U bundle is £229.85 and the Wind Waker bundle is £249.89.
The big decision is really the cost of those games by themselves. Wind Waker sells for £42.99 and Mario Kart 8 sells for £38.00.
Based on those numbers, the MK8 bundle is definitely the most cost-effective purchase at this point in time!
Amazon UK has reversed the MK8 bundle back to £229.00. This is still a good deal compared to the Wind Waker bundle.