How much would you pay for Mario Kart DLC?

There are only a couple dozen tracks in Mario Kart 7 for 3DS, so I got to thinking about DLC downloadable tracks for the game. I think I’d be willing to pay around $5 for each new “cup” of four courses. Of course, this would create a question around the inclusion of these courses in the online aspect of the game.

Do you think this is a good idea and how much would you be willing to pay?