Watcher Do you have a link, if that's no trouble?
I don't really want to get into advertising for specific eBay sellers. But anybody with tens or hundreds of thousands of transactions and an approval rating above 90% and a good return policy would seem like a reasonable risk. To be clear, even a reputable seller might miss a defect every now and then, so the return policy and the return process matter.
Be sure to thoroughly test a device: test Bluetooth, test Wi-Fi, test the speakers, test the microphone, test the face sensor, test USB data transfer, test GPS, test all cameras, test the accelerometer, test the SIM tray, test NFC if you plan to use it... all right away.