Inboard Power

Greetings,
The inboard issue popped up with mention of the Subaru. When I looked into this before (superficially), it seemed that the actual hardware
to get a shaft through the hull with bearings and seals was VERY spendy. Has anyone actually done this in a "shade tree mechanic's mode"?
There are lots of 40 to 80 HP motors that would make sense. (In my opinion, Captain Woody's lawn mower conversions are not effective.)
Any details about what is needed and approximate costs would make for great reading, costing many of us hours of design frenzy dreaming
every time we see a rolled Honda or...
God Bless,
Jim