Cujo's #s are right on.
But his calcs miss the chems used to wash, and other overhead you incur.
Fences use a lot of materials and therefor pricing has to reflect those costs plus the additional you need to make.
They turn into expensive jobs quickly, and some homeowners will balk at spending so much. At least that's how it is here.
When I threw out the $3/ft charge, it was meant as a bare minimum figure, and in reality a little too low for what the job is worth.
I don't let the customer supply my stain or tell me what to use. They are free to ask plenty of questions as to why my stains are better than any of the retail stains they can buy. Once they understand, most have no problem.
Even if someone is paying me, I won't use CWF. It's a great product to ruin your reputation, when it prematurely fails.
I think if you spend some time using the search tools on this board, you can get answers to just about anything you need to know about all your topics.