I did months of research on iMacs before purchasing mine, and I never came across one that was less than the price at the Apple Store. I got $100 off a printer (I chose a 99 dollar printer, which means I got it for free). Also, during back to school time they gave out free iPod nano's with the purchase of any iMac/macbook etc. Which is a pretty sweet deal if you ask me. Even if you have an iPod already, you could sell it on eBay and save yourself 200 bucks.
I don't know if you're a student or not, but if you are, make sure to take advantage of the student discount.