There is three ways to deal with rising prices of games.
1) Find a means to create cheaper games. Nintendo is going this route with the Wii and DS. They are trying to do everything they can to keep development costs down and create high quality games. This means is a short term answer...but one that is successful.
2)Enlarge the market of game buyers. This is very hard...with all the different rental programs out and so many games fighting for our money it is quite hard to increase the number of sales for each software credited. Nintendo is trying to do this by broadening the market...appealing to traditional gamers, but also reaching out to nongamers, and casual gamers. This market is untapped, but still has money to spend. This however, doesn't promise increased software sales units however. So you must find ways to make your games worth the purchase...which leads to...
3)Creating games with more quality and quantity of game. Several games are doing this by adding extra quests, remixed or harder versions of game, hidden characters, or other types of unlockables. The secret to this is not to use codes, but challenges to unlock the goodies...the balance is hard though, because you still want everyone to experience everything in the game. Another means to this quality and quantity I hinted at before. Create special behind the scenes footage, commentaries, anything that true fans of the game can watch and enjoy. These specials don't have to cost too much to produce, but will add alot of value to the experience. Just remember, don't go for cheesy and sparkling innovationy, provide real meat with the specials.
Basically, prices are going to rise...unless the market grows so much that millions of people are buying each and every game (like the movies) If that can happen, then prices can drop, because more people in the market are buying the product creating more cash flow.
Unfortunately, I don't see the market growing that much right now.