Dear Aunt TUAW,
My brother is getting one of those devilishly good lookin' new Retina MacBook Pro's. Should he order now and wait the 2-3 weeks? Or wait and see when it comes in stock at a local Apple Store?
Your loving nephew,
Do you need to customize your processor and RAM? You'll probably do better online. If not, and you're close to an Apple Store retail outlet, go ahead and look for one in-store.
Remember, the Retina MacBook is not end-user serviceable, so you'll need to purchase a unit with the exact memory and storage you'll use for the lifetime of your system. Auntie recommends buying as much RAM as you can afford. (Feel free to max out any specs you can handle monetarily, but Auntie's particularly a fan of RAM for best system performance.)
As to where to buy, Apple's online order system generally gets backlogged quicker than its in-store availability. Auntie suspects that demand for the new Retina Pro won't be as high as for that of a new iPad or iPhone, so store inventory should be steady.
Whatever you do, especially as you're planning to buy near the top of the Apple ecosystem, make sure you buy into AppleCare. Yes, this raises the base cost of a system by $349, but Auntie considers it an absolute essential for a Retina purchase, as well as for any MacBook Pro.
AppleCare greatly increases the likelihood that you'll have a good customer experience over the lifetime of your unit -- and Auntie rarely buys consumer warranties for anything. By purchasing AppleCare, you're buying into Apple's Genius Bar and telephone support ecosystem for a full three years. It's worth the cost differential.