Jack,
I would seriously consider Studiometry. I have used it in my photo studio for almost a year. It puts my husband and I on the same page and helps immensely with getting billing done quickly and accurately. I mainly focus on using the time-tracking and invoicing options, but I have found something new to use with almost every release. They update often and the support is great about getting back to you (No seriously though they do and this is a rare thing these days).
Kris