As a marine engineer who worked and both new build and refit side of the business, I’d say whatever price you pay for the boat itself, be prepared to pay same amount in 5 years for maintenance and marina fees etc.

Simon is the first person that came to my mind when I saw this post. Also the way you said UK Inbetweeners made me realize there’s also US version. Even the thought of it sounds terrible and I won’t even bother to check it.