In his article "Creativity vs. Quants" (New York Times, March 21, 2014) Timothy Egan perfectly describes the creative types in our world and their process:
"An original work, an aha! product or a fresh insight is rarely the result of precise calculation at one end producing genius at the other. You need messiness and magic, serendipity and insanity. Creativity comes from time off, and time out."
I use his description to better communicate to clients that I'm NOT a contractor, but rather I'm a craftsman, an artisan. Nor can I usually be accurate on when I can finish building the project because each one is always something unique to the customer.
When it comes to placing a price on the project I talk about "value" and also that each customer is kind of a modern-day "benefactor" or "patron" that can choose to pay me an amount of money that allows me to continue in my trade; be around for the next customer; and have a little down time in between projects to learn something new, experiment and grow.