Superb work.
Wanting to make a watermill myself, but will probably be a bit more 'fantasy'
As regard selling, I have sold a few bits/got comissions.
If you work out your hourly rate, then it's not worth it when you put a realistic price on it.
But, my way of thinking is that if I'm going to be making something and somebody wants to buy it, then my hobby is paying and I dont have to store it!
If I made the watermill to same standard, I would be looking to charge around £100, plus postage