I once had an art director tell me " I don't care if you draw it on toilet paper, I just want results". Sometimes I fell that thats what the art director or client thinks of my work; looks
at it, then uses it to wipe his behind. I do resdential design, including the construction drawings required by the building department; when I can get the work. I would not be doing that, if the person could get building permits with out the drawings. They see my work as
a waste of time and money. But will think nothing of paying a contractor or for the materials
to build their new home. Why, because the will have something real to look at in the end.
When determaning a fee, I obtain as much detail about the project as possible(I call this "putting a fence around the project") doing the work for a contractor or the client.
I approach the client explaining that the "foundation" for a project does not start by
placing forms and pouring concrete at the job site; but starts with a good design and construction drawings. That changing design features is less expensive on the computer; then having the contractor rebuild or change features on the job site. Getting the client to understand that your relationship has value, will help in establishing your fee. Including the quality of your drawings in your descussion with the client. Good drawings=less errows on the job site.
I hope this helps, Bob