Thanks to those curved sides, the Samsung Galaxy S6 Edge is a premium phone, and the handset comes with a price tag to match. If you want to get one from AT&T, you're looking at paying over $900. Fortunately, if you don't mind refurbished units, you can currently order one on eBay for $550.
While you may not be getting a brand new device, you still have your choice of colors. The seller is offering these things in black and white. Shipping is free, but devices will only go out to certain parts of the world. The US and Canada are covered, as is much of Europe along with Australia and New Zealand.
These are unlocked phones, so you can take them to T-Mobile here in the US. Just keep in mind that the two carriers don't support the same bands, so your data connection might take a hit in your location.