In the central Calif area there are different prices. The lowest is $25. At some the teacher gets it all and at others, the store takes a %. Some LQS will allow cancel of class at a minimum level. Others don't. Guilds with local teachers usually charge $25. Unless you have a following, 4 people in the class is a good size. Some guilds are taking teaching seriously and offer out of the area teachers at $50-$65 for 6-8 hours. The cost of putting on the class and lecture at the guild meeting can by up to $1600 so often the guild absorbs some of the cost.
I love teaching classes. The adult students learn a lot from each other, have more fun in the class with 3+ in the class. I have a minimum of 2-3 and charge $40/student. I get the whole fee. The class set up allows 10 students.