are best for everything but Towers. If you want a Tower, do a BTO from Apple's website. There is nothing like a custom Quicksilver to bring out the Geek equivalent of Muscle Car Mania. A BTO is the only thing I can think of that adequately offsets the instant gratification of a storefront.
I've been able to consistantly get free stuff by simple bartering with a catalog store over the phone. I was able to get 256 more RAM, an optical mouse and an extended warrenty when I bought my TiBook.
Be firm, be amiable...get more. Don't settle for what the stores are offering, you can often beat it by shopping around (compare tax, shipping, free stuff, etc.) and sweet talking a representative into a better deal.
Even if your sure your buying a new Mac, your not sure if your talking to a dealer. Just like buying a car.
After a long journey getting my 933mhz, I'm a firm believer in purchasing directly at an Apple Store (not online). Online is a pain unless you really want a BTO (which will take a few days extra to ship, usually). If you're within an hour and a half of an Apple Store, just go there. You'll ensure that you receive the product that day, you'll get to enjoy the lovely store, and support Apple's retail project (sort of).
Also, you can get education discount at the stores (started two weeks ago) if you're a student, which means even less of a reason to go through online retailers.
Lastly, the Apple Store gets new products immediately, so you can pick it up the same day that it would normally start shipping from a retailer or Apple itself.
Course, in some places tax is greater than others. Fortunately, Mass only has about 5% tax, which isn't too bad.
when I got my G4 I priced out many configurations. the great thing about ording online is that offten you dont have to pay sales tax. when your spending as much as you are on a comuter... this adds up. I ended up taking the Apple student discont over no taxes. The discound basicly takes care of the taxes so its not that big of a savings but I didnt get to BTO. I didnt need a super drive at the time (now I wish I got it) and that saved me a cool $400.00. if you not going to build to order... i would order online. You can often get deals like free shipping, no sales tax, and free RAM upgrads or printers. There is something to say about walking in to a store and leaving with a New Mac... you get it that day and you dont have to worrie about damage as much (well.. i know guys that work at Best Buy.. what goes one in the back and on the dock would shock you).
I got mine in one pice and one time from Apple. and you know dam well that I was at the Fedex tracking site every 30 min to see the statis of my Mac.