In most cases, price will reflect age, nothing safety oriented, unless some major part is missing.
Of course I see ~1980 boats going for $20-30k too, so I have to wonder if a less expensive boat (late 70's Hunter or C&C for <$20k) is asking for trouble. Worst case and some problem develops on a $15k boat, I could still likely sell it for $5-10k, right? With a $40k boat, there's more to loose it seems.
We got our 85 30' boat for just over 20K, could have spent less if we wanted, but it was clean, and something we liked.
One thing I've seen is boats with PO's who've gone crazy, installing radar, multiple hardwire GPS units with a "server", etc. Stuff that I'm sure was originally expensive, but which today seems either pointless (radar) or easily obviated by a $200 pocket color Garmin etc.
Any boat from the 20' with a small cabin on up can sail here in puget sound, up and into the sanjuans too!
I sailed a Santana 20 on Lake Washington once in choppy water, and took quite a beating. Last weekend my (admittedly pregnant) wife and I rented a J24 out of Orcas and sailed/motored around between there and Jones/Waldron. At one point a jackass in a powerboat (yes, really!
) blew past us and his wake jostled us a bit, enough that the Merc 5's prop came out of the water once and my wife kinda freaked at the motion. Back in June we passengered on a daysail on a C&C 36, and powering back at night we had (guesstimate) 3' swells that she wasn't doing too well with, so the comfort factor is important to me - especially when the baby starts coming along. I can join a club and maybe end up on 25' boats a lot of the time, but am concerned about how the comfort angle for the two of them, especially overnighting.