So I sold off the last of my ASIC a few years back but have been considering buying a few new toys recently. I've found an s9 that does the 13.5 TH for sale as new. They are only asking 1600 USD. To me this is fishy as hell given the prices I've seen on ebay. They claim to be shipping from the UK. Worth the role of the dice?

Depends where you found it. eBay is safe for a buyer, I've heard not safe for a seller, Amazon is safe for a buyer. Are you paying in coin or credit card?