The #1 rule when it comes to consumer electronics is this: Nothing holds its value forever. The latest device to see its price hit an all-time low is Samsung's global dual-SIM variant of the S8 (SM-G950FD), which has just hit $430 on eBay, falling a further $45 since two months ago.
There are a few necessary caveats to bring up when discussing the international variants of Samsung's flagships. For one, their warranty is almost always not applicable in the US. They also get Samsung's Exynos chipsets—the 8895, in this case—rather than Qualcomm's Snapdragon series. That change also removes CDMA support as well as band 29 and 30.
Apart from that, you get the same specs the S8 is known for, including the high-resolution AMOLED screen, 12MP camera, 4GB RAM/64GB storage, and 3,000mAh battery. The only color they're available in at the time is Gold, but for $430, it's hard to complain. You can always put a case on it.