I think part of this (from a buyer rather than trade perspective) is not really knowing what the results will be! I would pay more when I have confidence in the trades person.
Some of the more ‘basic’ trades – painting/plastering etc. I have a plasterer that I know (came from a recommendation off here) and I barely look at his quotes now. I know he is fair with pricing rather than cheap and I also know that he will do a great job – that removes any doubt/stress I might have about the end result and paying a bit more is a no brainer.
I’ve had cheap painters over the years and they have done an ‘OK’ job. A recommendation from the plasterer above has led to a quote from a new guy, his price made me check for typos! However, I’m told by someone that I trust that he’s good, I’ve now met him and was impressed with the level of detail/questions in his approach and I’ll be going with him.
Its about reducing risk of the unknown. OP – your idea of some typical jobs with rough pricing is a good idea for your website but maybe you also suffer in that your work is long term? Everybody employs painters, not so much cabinet makers? You need to do all you can to take stress away from the buyer (in terms of quality assurance).