My thoughts are that NADA gives a value to the boat, but its up to the owner to make or break this price. Most values are low, and are adjusted do to market values, you could have a boat tgat needs a ton of work and tge seller assumes that the fair value of the boat is what NADA suggest, where a boat that is up to par takes a big hit due to lower numbers.
I have owned a Catalina, i have owned an Ericson, the build quality and workmanship between the two boats in my eyes are non comparable. The Catalinas I think have a higher value due to the fact that thousands of the 30 were made, the only production boat with higher numbers I think is tge Catalina 22.
If you survey the boat you are buying, follow the survey and upgrade recomdations, and keep the boat current, any boat should hold its value. The funny thing is that you can buy a cheap sailboat, fix her up, and enjoy...
Another note; a new suite of sails can be alot more than the cost of the boat. Our 33 with all new sails would be 2500-3000 for the main, 2700 for a 150, 2200 for a 130, 2000 for a 100, and 2200 for the spinnaker. In the last year we have spent over 10,000 in getting her back into shape, thats just the floor, bottom job, running rigging, and new a/c system. We have another 2700 in new cushions, and we still need to fix and update some stuff. Also for tge boat to sit in the water is 250 per month, 400 to haul out in tge winter time...
The boat cost is nothing........