I run a Skype coaching program for communications, speech, and debate. A few keys we have found:

1) Effective Tracking – Basically CRM, though we use a Google spreadsheet.
2) Quality Control – Internal and external monitors
3) Centralized Billing – Let the coaches coach
4) Common Feedback Repository – Scale by writing down regular comments and exercises in a way that all coaches can see

Our model works more like music lessons (e.g. $65/hr, $100/hr, etc), but we have both long- and short-term participants.

Happy to share our lessons learned.