I like the idea of making these things as well, and I do a fair amount of customization on my own equipment, particularly if it's wood. If it's metal, I send it out.
There is a contemporary version of the Grafmatic--the Fuji Quickchange--which you can get from Robert White, and maybe Badger Graphic, as well as in Japan. I love Grafmatics. I have three and just bought another one. I don't own any other kind of 4x5" holders.
I'd really like an 8x10" Grafmatic style holder, or possibly a Mido II style holder for 8x10" and 11x14". These were super thin holders that fit into a spacer in the camera so that you could fit two or three in the space of one holder. The first version was notoriously difficult to load, but the second version was supposed to have fixed the problems. They are hard to find and always sell at a good price.
To be fair, the handmade wooden holders do have a lot of labor in them. I suspect S&S keeps the cost lower than AWB by putting a fine, smooth finish only on surfaces that are critical. I noticed on mine, for instance, that the darkslide handles had some gouging that wouldn't pass on fine furniture, but didn't impair the function of the holder, and there were some rough cuts hidden by putting the rough side down that one would notice, if you were looking carefully, but that would not impair the light-tightness or registration of the holders.