The Retina MacBook Pro has seen increasingly longer shipping estimates since its announcement, most recently reaching up to four weeks. Over the last week the shipping times have steadily been decreasing. In mid-July shipping times improved from 3-4 weeks to 2-3 weeks, and more recently went down to 1-2 weeks. Now shipping estimates for the Retina MacBook Pro are at its best, shipping in only 5-7 business days in the US and UK.
The better shipping estimates come at the same time that Apple has also expanded configuration options for the entry-level MacBook Pro with Retina display. Buyers can now add 512- or 768-gigabyte solid-state drives to the base model with a 2.3 gigahertz quad-core Intel Core i7 processor.
Obviously, you can pick it up on the Apple Store.
Source: Apple and Apple Insider