The Galaxy S8 just launched a few weeks ago, so the discounts are nothing like you see with phones that are months old. Still, there are some deals to be had on the GS8, including this one on eBay. For $689.99, you can have the unlocked international GS8 (G950F). That's about $100 cheaper than most retailers.
The listing on eBay is a little ambiguous on the hardware (it lists both SD835 and Exynos), but this should be the Exynos version of the phone. The rest of the specs are unchanged; 4GB of RAM, 64GB of storage, 5.8-inch AMOLED, and so on. Importantly, this phone only works on GSM networks, and it's region-locked to the Americas. To use it elsewhere, you have to place 5 minutes of phone calls with a SIM card from the right region.
You have your choice of black, gold, and gray colors. This listing comes with free US shipping, and there's no international option. Sales tax is only collected in Florida and California.