It appears this may have been a special offer limited to select customers who preordered a different color that was delayed, and that the web page was set up to never run out of stock. The shipping date may be completely wrong, as well. We're waiting on a response from Best Buy to confirm, but given that it's a holiday, we're not expecting it until Monday. We advise you not to order.
If you head over to the Best Buy website right now, for $499.99, you can get your very own ASUS Transformer Prime 32GB Amethyst Gray edition on its way to your doorstep from Best Buy's warehouse on Monday, December 27th. The tablet has been notoriously hard to find on the web the few times it has popped up (unless you want to wait 4-7 weeks on Amazon), with only a few lucky preorder customers and quick-clickers getting in on the action so far. It's still in stock as of this writing, but we'll update if it sells out. Sadly, the keyboard dock is still not available anywhere, it seems.
Reddit via Liliputing