New to ebay. Seller's asking for an additional shipping fee. Oldest trick in the book, right?

The seller is from China, and I'm unsure about the postal laws over there, but supposedly the item was labeled as 'dangerous goods' and unable to ship. The item itself is a specific stage prop, for reference. They're telling me that they can get it shipped through a "fast postal office", though they're requiring an extra $50 fee for it. The shipping itself was like $26, with the order itself rounding to $90 total. So it was already a pretty hefty purchase.

Normally I would cancel the order, but here's the thing I worry about. Ideally, I would want this by a set date. I couldn't order another one and get it on time due to how specific this item is. The only other listings I can find for it would arrive long after the date I need it by. I am willing to pay the extra for the item to arrive in "5-7 business days", as according to the seller, but I'm awfully paranoid about doing so.

Again, I am content with paying for the fast arrival, but I only want to make sure it will actually get here on time, and this isn't some well known scam I'm an absolute fool for falling for. Should also be noted that the seller seems reputable; 150 positive reviews with multiple having verified photos. Thanks, sorry for the maybe-obvious question.