We owned a semi custom 40 footer that started out as a pure raceboat, pipe berths, open head etc. But construction was high quality even if the finish was originally quite spartan.
By the time we bought her, someone had done a reasonable job of adding a real Vberth, enclosed the head and enlarged the galley. There was plenty of teak and the boat was quite attractive below, and we had the added advantage (over most production boats) of having absolutely top notch, oversized deck gear including 3 speed winches, full hydraulics etc)
During our tenure with the boat we further modified the interior (something almost impossible to do with a production boat with fiberglass liners) and then added amenities like a deck accessed anchor locker and a cockpit hatch to access the transom/lazarette area. Here when we cut into the deck for these mods we found excellent workmanship, tight laminates and coring, all evidence of good construction.
We paid a fraction of the price for an equivalent production boat, sailed her for 12 years, and sold her (admittedly upgraded) for about the same as we paid 12 years earlier. So whatever money we put into her we considered a user fee... over 12 years it wasn't a lot of money (maybe $10 - 12K total not incl moorage and insurance) Upgrades included new dodger, a major repaint, engine rebuild and some mods as described above. btw we are ardent DIYers.
Use of a GOOD surveyor is especially important here, as there will be no history like a high volume production boat. This is especially true if it's a first boat, and you don't really know yet what to look for yourself.
In the end, quality will tell regardless of the maker's name on the hull