I live about half an hour away from you over the border in Mass, and the going weekly rate for a full time kid in a home daycare I pay is $200, including breakfast, lunch, and snacks. I have another person who charged $35/day or $170/week.
It would be good to find other people who do what you do (watching one child versus a more official daycare set up) and ask them questions (i.e. taxes, contracts, any paperwork protection). I would locate some daycare paperwork online to see what providers require of parents, perhaps drafting up an agreement that covers your responsibilities and the parents.
My daycare contract covers things like your responsibilities (milestones, healthy food, rest), and clarifies rules on using/dispensing medicine, parent required weekly supplies, hours of operation (and late fees after X time), emergency contacts, and more.
Good luck!