[quote name='gizmogc']Mario Party's never really lower because they are almost the same game every year. If they were to lower 4 and 5 to $30, it would hurt the sales of 6 and the upcoming 7.[/QUOTE]
You could say the same thing about most sports games, though, and look at the difference in price in the old versions.
It's hard to say if it'd hurt the sales or not. On the one hand, people like us might see that the old versions were cheaper and just go with those. On the other hand, a large number of the clueless public might see a big difference in price and assume that the new version must be much better if it's selling for so much more.