I agree with Judy, if you start this when do you stop? I let the parents know that I need to supplement the family income, if I did not I would not charge at all. My family relies on my income.
In BC we have a subsidy system and if you are not able to afford daycare the Provincial government will help. All you need to do is make a phone call, go in for an interview and you will get a percentage of your daycare fees paid for. I charge the parent for anything shortage in the subsidy paid to me.
Have the parent call to find out any information from the provincial government.