Starting to give riding lessons?

okay so heres the story.. im starting to give riding lessons but the only problem is I dont have a ring. Do you think I should invest in getting a riding ring and if so how much do they usually cost? What other things do you think I would need to get this started? I have all the tack but I would probably just need to get a childrens saddle. Should I just get one or more? Also what should I charge and should I be the one to supply helmets? Thank you for your time