No use beating a dead horse on this one so I'll be brief.

First, the additional $100 for electricity for one month for training a client is unreasonable. You should also request in writing that you be paid the $570 or so that you are owed for training the client. "If" you wish or have to take this case to small claims court at a later date, you should be able to demonstrate that you at least requested payment.

Most important, as you already know, you should not start work at any facility without a written contract that clearly spells out items such as electricity, client referrals, etc. Just my ideas on these matters, not a legal opinion. I've been in the fitness biz for a short time but I have been in the real estate business for more than 30 years and I never touch anything without a formal written contract.

Best of luck,

Curt