There will always be somebody who wants a better deal. I had a lady once ask me if I would give her two for the price of one because she had twins. I told her I wasn't there and didn't have anything to do with her having twins.
As for charging by the hourly rate, I always go with what it costs me to make the first one. No matter how fast you get or what kind of jigs you use, you are still putting forth the same work. You just get paid a little more for every piece after the first one.
I use a formula that is materials plus hourly rate plus a percentage for overhead. It has always worked for me, and I get few complaints. And I don't work for cheap.