It took a few weeks but Amazon now has the 27-inch iMac with the Retina display. You can click this link to go straight there. The warranty is through Apple whether you buy from Amazon or the Apple Store, or anyone else, so you can simply shop on price. Comparing identical models, Amazon’s price is better than the Apple Store’s.
Amazon also has the new Magic Mouse 2, which improves on the original Magic Mouse by having a built-in rechargeable battery (and you charge it using the included Lightning cable, same kind your iPhone uses– and two minutes of charging gives 9 hours of use!). The Magic Mouse 2 is also a little lighter and it glides a little more smoothly than the original. Note: you’ll need macOS 10.11 or higher to use all its features. You can click this link to go to the Magic Mouse 2 page on Amazon.
If you need a wireless, rechargeable keyboard, Apple’s Magic Keyboard fits the bill. It recharges with a Lightning cable (included) so you’ll never need to replace batteries.