When buying a mixer watch the wattage. You want a high wattage. Some Kitchenaid have low wattage thus the lower price. Each model may have different wattage so check that when wondering the price difference. At least over 550 watts for dough and stiff batters. There is a new model of Kitchenaid, the stand mini. Perfect for smaller kitchens and everyday mixing.
http://www.kitchenaid.com/countertop.../stand-mixers/
Forgot to add I have the Kitchenaid Professional 600 lift bowl in bright red. Love this mixer. I bought my DD one. My other DD cooks by phone but she will get mine oneday.