Samsung's trade-in program for the new S10 flagships has been mostly limited to older Samsung flagships, with total trade-in value topping out at US$550. The company is eager to ship as many units of the S10 phones as possible, though, and is now allowing buyers to trade in any smartphone and get US$200 off. There are a few conditions, however.
https://www.notebookcheck.net/You-can-trade-in-any-working-Android-or-iOS-device-and-get-US-200-off-your-Samsung-Galaxy-S10-purchase.415775.0.html