I'm won't say anything concrete. I'm interested to see what others might say.
But in big picture terms homemade, custom made boats can bring a good price. But only when they are brand new. Which might work for insurance purposes.
But for reasons I can't explain with words homemade boats lose their value quickly. More quickly than factory made boats. It's one of the reasons I went back to building houses. And then on to other things after that.
The best prices right now are all associated with big decked white water boats. Of which there is no factory made. There have been a few but right now I don't think you can buy one. If you want one you have to build one or hire someone. Ken Hankinson makes a few every year, no? He does good work too. And he gets a lot for them. Decked white water boats hold their value too, perhaps because there are so few of them around.
Homemade open fishing boats, on the other hand.............