I can see what you mean. These are expensive just for a measuring or reference tool when experience is better most of the time.
I got the small one as well and was just curious of the others ones out there. The hook scale is more beneficial to me as I find hooks lying around everywhere and the scale helps me sort them.
I would be interested in finding or maybe actually producing one that has a standard hackle gauge, Hook scale like the DuBois with details on lengths as well as size, wing scale for sizing wing material, tail scale for measuring lengths of tail material, and a "wet"/"dry" fly scale. I am thinking others may find it useful as I think it may be. Will experiment and see how it will turn out.
I found three others looking around today...the first two blue ones are japan made and $30 each. The other is in Montana (Icon Fly Stages
) about $20