Why can't you have both?
The games can be completely different.
I understand offsetting the cost of the Wii but perhaps he'll accept payments {so not such a big purchase at once} so you can keep them both.
In our house {in an undisclosed location
} we have pretty much all systems. Some games just aren't available for some systems.
And me, I have a DSLite. Love it. Bought it for one game. It's all I play. So far.
Good luck on your selling it if you don't change your mind....