that combined with a rather small market/demand equals a high price,
I'm not quite sure I follow this. You guys are makeing shaker conversions, and I assume you are selling enough to make it worthwhile. Flat hoods are becoming scarce because everyone wants a shaker. Several new companies have popped up to make complete hoods.
Now, unless everyone that is buying one of your kits or a repop hood is just doing it to replace an existing "real" hood, then the demand for the other components would be quite low. But, in reality, I believe that most of the hoods are going for aesthetics, conversions, clones, etc, so in that case, the demand for the shaker components should be pretty close to the demand for the hoods. I'd be the first in line to buy one of your kits if I wouldn't then have to fork out $3k for the rest of the components, but in reality, I have other things that I need to spend that money on.
Since there are people out there that are making the components already, they have obviously already suffered the costs of tooling. Why not gather these people together to provide a kit? Their business would increase, and so would yours?
You have to remember that once the people who want a shaker for aesthetic purposes drop out of the picture, the only market you will have left will be clone builders and restoration replacements, and those numbers are pretty low compared to the people who want them simply because they like them.