I charge 1.25 cents ($0.0125) per square inch, with a minimum of $60, for e2e/pantograph, with varying prices for custom, up to 3.5 cents ($0.035) psi for heavy custom.
Like tstransky, I do have batting available, and lately have even offered wide backing, as that seems to be a better deal all around for both me and my customers. My turn-around time is usually 2 weeks or less. I don't charge a "per bobbin" fee nor a "loading fee" (which some in my area do).
If a top or back comes in wrinkled, I will either NOT quilt it or will charge for pressing (and I really HATE to iron, so it's pretty steep!). Needless to say, it only takes once for a customer to forget to press their top/backing.
I have seen cheaper prices online, but I often wonder at the quality of the quilting and thread.