I don't feel that Wii games are sensible priced. Actually if you take into account the development time for those titles then they are overpriced.
The manufacturing cost is not a factor for retail price, it is a factor for profit margins. The only factor for retail price is "How much are people will to pay for it". As long as they're selling, neither Wii games (or console games in general) or the PS3 is overpriced - although they may be to expensive for you. I almost bought a Wii, but for the lack of a decent release schedule.
It's worth it just for Zelda: Twilight Princess. Everything else is just an extra bonus.