I agree with Bob Boudreau that, "It seems that a few sellers have an unrealistic sense of the quality and value of their assembled models."
I think we have established in the forum that scratchbuiltmike does not belong in this category. Out of curiosity I checked his e-Bay feedback to find nothing but compliments and pleased buyers. After a second look at the photos, they're not as fuzzy as they seemed at first, and looking at them carefully it's clear that there is a high level of detail on the model. It appears that Mike does some very nice work that adds value to the models he assembles.
However, I was at a show this weekend where a modeler was selling a matched set of custom painted Kato GP-35's decorated for a local shortline. It was a simple single-color scheme, but it was clearly the wrong color (should've been a Santa Fe blue but was more like Conrail Blue) and the paint was poorly applied. Worse, the decals were not located properly on the hood, and had plenty of bubbles underneath. There were no prototype-specific details added. I'm sure he had fun doing the work, but in my opinion he had detracted from the value of perfectly good undecorated Katos, not added to their value.
I was amazed when I saw that he was offering them for $200 each (almost twice the retail price), marked down for the show from $250 each. I'm sure he is a nice enough guy and not trying to rip anyone off, but I believe he has vastly overrated his skills and/or vastly underrated the market for custom work. I'm know he's not alone.
Tom