I've been saying something to that effect for years and I'm glad it is finally being discussed openly. It is not a knock on the hours of work by talented smiths, custom work is a personal thing often and you may not find another person who values it as highly as you do. In the sense of the marketplace, it is a decision you make as a buyer when you might commission a build, that if/when it comes time to sell, be prepared to get back less than you paid.
The canon sabers have universal appeal, so selling an OM Obi TPM isn't difficult. I would also like to think most collectors intend to keep these works of art, but all too often, after a short period of ownership, they are up for sale again. In many situations, each time a saber passes hands, based on the time since it was created, availability, and any advances in technology or skill since then, the price will often drop. I don't think it is a problem, just the nature of collecting, but it does seem that a lot of collectors in our hobby do not understand this, list sabers for too much and wonder why, and often get upset, that they don't sell.