I've never heard of any legit engine manufacturers or dealers who post prices on their websites. They may be out there, I haven't found any even when I was looking to repower a boat. I have heard of dubious offshore deals which I would not pursue as they usually ended up poorly. What I do know is Yanmars are generally more expensive than Beta and Nanni which use Kubota blocks, and a few years ago a ~30 hp Yanmar with transmission was about $24K.
Yanmar in particular, controls distributor territory. Call the nearest Yanmar dealer and ask.
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