Definately worth the $$. Go with the Kitchenaid brand - they're built to last forever. Some people are still using the Kitchenaid mixers that they bought in the 1950s.... that says a lot about the quality of the product to me.
I have the 5 quart - wish I had the bigger bowl sometimes, but the 5 quart does the job most of the time. Don't bother with the small one. I've seen it in stores, and I've always thought it looked "apartment" sized.
I actually had a problem with one of the attachment things that went on the front (the nut grinder got bent) and I called Kitchenaid customer service, they sent me a new part no problem, no charge.
The only thing I wish I had bought when I got the mixer was the bowl shield, so I could add flour when it was running without risking taking a flour shower.
As far as shopping for one -- I bought mine at Kohls. Sometimes you get lucky with sales - and also with coupons you can save a lot of $$ that way too.