Have you considered using a US vendor and having them FedEx it to you? Trans Atlantic Diesels
(no affiliation) in Virginia quoted me $1,700 US for a brand new HBW-125 recently. They've always been a very good and reputable vendor to deal with. The cost of the HBW-150 should be only slightly more. Three day international shipping
would probably be several hundred dollars, but sounds like it would be worth it in your situation if they have the part in stock. If they don't have it I've heard good things about Harbor Marine
of Everett, WA and Federal Marine
Transmissions of Countryside, IL as Hurth
dealers though I don't have any personal experience.
Some people have had luck getting Twin Disc transmissions to drop in place of a Hurth
. It's an avenue worth exploring but measure carefully.