Well if you are in the market for a new laptop, there is nothing quite like the Mac Rumors Buyers Guide (http://buyersguide.macrumors.com/) which basically tells you if a model is obsolete or there is something coming.
Once you get a green light from them (literally!), go to the Apple Insiders Price Guide (http://appleinsider.com/mac_price_guide/) and get the lowest prices and don’t forget to compare with the Apple Education store if you are lucky enough to still be in school.