I came across this article, for persons interested in buying and restoring an old boat. I think it has some very good advice. I agree, it is a costly endeavor but to some people it is the only way to go. We bought our "old boat" not because it was a financially sound decision, but because we couldn't find a boat with a better layout and living space.
https://www.docksidereports.com/fundamentals_of_restoration_proj.htm