Amazon does carry sealed product. They already have a listing for the 2019 Gold Sarcophagus Tin.

https://www.amazon.com/Yu-Gi-Oh-TCG-2019-Gold-Sarcophagus/dp/B07QTQYK11/ref=sr_1_1?keywords=2019+tin&qid=1564719504&s=gateway&sr=8-1

TCGPlayer and EBay are also popular choices for sealed product. Just make sure to buy from high-rated sellers to avoid scams.