I know it's only a few dollars, but evidentally GLD has also decided it's cheaper to send products to the UK and have them shipped back to the US than just ship to distributors/customers in the US.

$22.50 - Amazon US https://www.amazon.com/Casemaster-GLD-Products-Plazma-Zipper/dp/B084KZFQJZ/ref=sr_1_6?crid=15040Y6XF28LQ&dchild=1&keywords=casemaster+plazma&qid=1618410338&sprefix=casemaster%2Caps%2C281&sr=8-6

$17 - Shipped from DartsCorner https://www.dartscorner.co.uk/product_info.php?products_id=46590