Do you have other clients? How are you charging them? I would ask her:
- How many patients do you see in a week?
- Are you planning on growing? At what rate?
Also ask how much she charges on average per visit and what is the average reimbursement? What will you be doing, strictly billing? Verifying benefits?
Once you know these things it will be easier to come up with a fee. You should consider that you need a minimum though to make it worth it. If you are just starting out the experience will be very helpful so you may not need the same minimum you might require if you were not just getting started.
Good luck!