Historically, Apple doesn't usually drop the prices of their machines. They usually just release a new/updated machine at the same price level. Any remaining "old spec" machines get put on the "hot deals" section of their online store at about a 20% discount.
Sometimes, if a model has been out for awhile and isn't selling well, Apple will give it a price cut. Other times an originally overpriced item might get a price cut to help it sell. Sort of like what Apple did with the 60 GB iPod that was originally about $500, now it's $399 and has video support. Another example is the Aperture 1.1 RAW photo sorting program which is now cheaper than it was when 1.0 first came out.
Your best bet with Apple is to wait for the new models to come out and buy one from their website with your student/parent/educator/gov't discount, saves 10% - 30% off list price on hardware and 30% - 50% off list price for software.
