I would guess for around $500. A better solution might be to donate it to a
local charity

That always sounds like a better solution than it is. As a guy who worked the
"boat donation" end of things for a while, I can say that most non-profits
don't want a junk boat any more than anybody else. Lots of folks give up trying
to sell a trashed out boat, car, or what not and decide that they will be doing
humanity a favor by graciously donating the worthless hulk to the local
charity.