A good book to learn about homeschool co-ops that are class-based including a step-by-step guide is:
Homeschool Co-ops: How to Start Them, Run Them, and not Burn Out.
Look inside here.
Learning in Family Education Co-op Classes (LIFE)
At LIFE Co-op, members are asked to sign a Co-op Agreement, a Waiver of Liability, and pay a Co-op fee, in addition to class fees, if there are any. The Co-op fee is per family and the money collected is given to the church or facility for use of the building. This primarily covers the cost of electricity and other expenses. Some facilities have a set rate, others do not. Typically, the fee is $20 a semester depending on the number of families participating.
Class fees are typically from $0 to $10, some being higher for costly supplies, most are less than $5. Class fees cover the cost of supplies. None of the parents receive income for teaching.
If you are thinking about starting a homeschool co-op based on classes, my suggestion is to start small. You can read my previous post about how LIFE Co-op Classes got started by clicking here.
If you are looking for class ideas to teach in a co-op, I will be posting examples of LIFE Co-op schedules of classes. The links are here for your quick reference: