It's only like $25 cheaper in Japan. And most people in Japan are buying Wii Sports at retail for more than that. America by far got the better deal here.
In any case, you're going to be waiting a LONG time for a price drop. The system is still selling out, and they are not going to drop the price while that is happening.
Edit: Also not sure how you can complain about price when you own TWO PSPs.