I am buying my Ipad2 at Best buy because you can get it interest free for 18 months by getting their credit card. That comes to about 30 bucks a month (tax included)! You can't go wrong with that.
Target would be my next best choice, if you have cash, because they will give you a 5% cash-back if you use their credit card. So you would buy the Ipad2 with their credit card then pay it off at the end of the month.
The Apple store gives you free engraving and free shipping. But, if you engrave it, it will kill the resale value. Free shipping is great if you live in farm country.
Online would be good because you will save on tax.
Any other ideas?