Unfortunately, not that many. In fact, most games typically sell less than 150,000 copies according to a New York Times article, where Nintendo of America’s head honcho Reggie Fils-Aime shared this interesting information. Fils-Aime said “[one million titles] was a lower threshold than for the other consoles,” and to make that number possible “[Nintendo] deliberately did not add high-definition capability to the Wii so games would be cheaper to make.”
According to NPD figures, only 16 titles have sold more than a million copies, and that’s from a list of nearly 500 titles. Of those 16, nine of them are first party, and if you follow the Nintendo Wii even slightly close, you can probably guess the majority of them - Wii Fit, Wii Play, Mario Kart Wii, Super Smash Bros Brawl, etc. The grand king of Wii games is Wii Sports which has sold more than 40 million copies to date worldwide, making it the best selling video game of all time (although it's worth noting that it's a pack-in title in every terriorty outside of Japan).
Wii games sell new for typically $50 USD or less, while PS3 and Xbox360 games are in the neighborhood of $60 USD or less.