Well, I don't know how much you should charge, but I do know it cost me close to $200 to get batting, long arm quilting and binding on a twin quilt top I made for my grandson. I don't know if that is typical, cost may be lower in some parts of the country. And I don't like mailing the quilt tops -things do get lost in the mail.
Others may be able to give you better information. As you said, it's a lot of work, a lot of time and time is money!