It's all part of the technology being used in these games, and to help the company gain profit.
Think of it this way:
It cost money to make things, yes? Well, Nintendo and all the other gaming companies like to stay with the latest technology available to them. This however, costs them a great deal of money to use and engineer into the product they want. Now that Nintendo spent all of this money making a new system (like the Wii), they need to get it all back, and some extra to use later for games and even developing the next system. To do this they must put a higher price than what they spent to gain this money (usually 10-15%). When the items go to the market, they cost more to help the developing company.
Which in turn means that if they did make prices cheaper, then they wouldn't have money to support later games because they don't gain any money back. In my opinion, I wouldn't like to see nintendo go out of business. Would you?
Think of yourself in as the manager or owner of a store,
Would you like to make money? How would you do this when you're spending all of your money buying the products to sell? You couldn't sell it for the same price, you would eventually run out or continue to not gain anything! I'm pretty for sure you would want something for all of that hard work you put into making that store.
On a final note, games don't stay at the same price forever, they eventually drop because that game and it's technology gets cheaper, also, if it doesn't sell well, it also drops faster, so complaining about games' prices is almost obsolete, because you could just wait about a month or two to get the game for cheaper.
Sorry for having such a long opinion, but I felt it was necessary to express clearly the situation that you may not be seeing.
And to answer the question directly, the prices in the U.S. are about $50, about 50 Euro in Germany.
