You should never buy a $20k boat which is 20 years old though. That's a death trap.
Ahem. I did that, except it was 40 years old. It is also extremely seaworthy.
Was it wood or fiber?
Wood can be fixed easily. Fiberglass can get fixed too but harder. A 40 year old fiber boat can be extremely dangerous because of osmosis unless it was maintained well during all those years. If the owner checked the levels of osmosis constantly and took precautions, yes, it can survive without any damage. The stuff on the boat will be old too. Sailing clothes, metal pieces, ropes... They all fall apart in time even if you don't use them because of fckn salty air. You'll need to replace them eventually. I'd prefer to get them all new without taking any risks. But that's just me.
A 15 meter boat is Too Damn Big. If you can't handle it on your own, in a stiff breeze, don't even bother. If a 30 footer is too small for your crew, then better to get two boats instead.
See that's what I'm talking about. That sounds like a yes vote for a new thread! It seems like there are a surprising number of people here who are interested in yachts/boats.
Once you get into boating, everybody knows, it is never big enough. You'll always need a bigger boat.