The Galaxy S6 and the Galaxy S6 Edge are the best phones Samsung has ever put out, and if it wasn't enough of an incentive for people to grab one and upgrade based on what it offers, there's now more of a reason to pick one up for your next device as Samsung is offering a $100 rebate to those who buy one of those devices at full retail. If you're looking to stick with your carrier but aren't willing to extend your contract to buy this device, full cost is what you'll be looking at for out of pocket, but that isn't so bad when Samsung is willing to give you a little money back.
Here are the details for those interested. Samsung is running this promotion for people who buy the phone at full retail only, so customers who buy the device with contract pricing won't be eligible for the promotion. There are no limitations on carriers, so you can pick it up from whatever carrier you wish, and Samsung includes purchases made from other retailers as well although they don't specify which, the terms and conditions merely states "from a participating location." Considering this, you'll want to double-check with wherever you plan to buy it.
This is a promotion for making a purchase on the 64GB variant of the device, as Samsung is trying to supplement the difference in cost for customers to choose the 64GB model over the 32GB model. Where things become interesting if you're a T-Mobile customer in particular is that you can pick up the 64GB model from T-Mobile for the full retail price of the 32GB model due to T-Mobile's own "Free Memory Upgrade" promotion, so you save some money here and you can send in the rebate information for the $100 back from Samsung. The promotion began yesterday and it runs through until July 5th, ending at 11:59pm eastern standard time, which is 9:59pm here on the west coast. Samsung doesn't mention whether or not this works with online purchases of the device, like through Amazon for instance, but if you were already planning on buying the Galaxy S6 or the Galaxy S6 Edge through Amazon you may as well fill out all the details to pick up the rebate anyway. You can find all of the information you need through the source below which leads to Samsung's "Ultimate Upgrade" promotion page.