Legal Question in Business Law in California

Re: client missed appointment, won't pay

Make her pay in cash and in advance the next time she makes an appointment. It's probably not even worth it economically to file a small claims lawsuit or hire someone to collect for you.

Re: client missed appointment, won't pay

I agree with Mr. Cohen on the practical solution, but you asked for a theoretical answer. This is a breach of contract, and in theory you could sue for and probably recover compensatory damages -- not necessarily $60, maybe more, more likely less, but (in theory) whatever your loss was. Usually losses are measured by the difference between what you would have billed and your costs for providing your service. There are other principles that could affect your theoretical damages, but the basic idea of contract damages is to place the non-breaching party in the same position (no better, no worse) than she would have been in had the contract been performed. This is called benefit-of-the-bargain damages.