I like to buy locally if at all possible, just because I'm the kind of person who wants to be able to touch a product before I buy it. However, in buying a new Mac, another big factor comes into play, and that is reliability.
I just bought a 15" Aluminum Powerbook, and I got it at the Apple Store in Salem, NH. The reason is that the Apple Store will let you return a machine you've bought within the forst 10 days for any reason. That includes defects. It seems that the build quality of Macs have gone downhill in the past few years, and if I bought my PB from a regular local retailer, and upon opening it up found the now common spots on the screen, or any of the other defect, it would be an Apple repair issue, whereas at the Apple Store I can just get it swapped out.
It's too bad that's the way it is, because Apple is just damaging the small dealers with policies like that.
Where Is The Best Place To Buy A Mac?