Quite a lot of stuff. Half of it is retro games for Virtual Console and another half is original Wii downloadable games.
The price are all in points. I'm not sure what's the cheapest, but for NES games it's around 500 points and N64 games can be up to 1800+ points.
You can get point top-up cards, according to some forumers GH had some, not sure still have or not, you can try to PM Djinn and ask. Most people here use a good CC and "Brazil Hack" to get their points. But for me now think I have to use top-up cards oredi. Not to say CC beku, but aunt scold for buying too many things oredi