Edited March 8, 2017
at 10:20 AM
Looks like basically the same deal as at Costco, but with free shipping (Prime, etc) from Amazon.
So now you have a choice -- pay tax on $499 at Amazon, or pay shipping and tax on $579 (pre-sale) at Costco but get the benefit of the Costco extended warranty and whatnot.
In other words, lower all-in price via Amazon but better warranty (and easier return, if you're near a store) thru Costco.