That clinic may not even have the abortion pill. They may be able to prescribe it but they may make you go to an outside pharmacy. It really depends on what your state's rules are.
If they will not prescribe it due to parental consent, it is possible to get a court hearing and fill out the paperwork to have a secret court process to determine if you are capable of making your own medical decisions regarding the pregnancy. They nearly always grant you the right though to make it without informing your parents, partially because once you have a baby you would be capable of making your own decisions anyway.
If they cannot prescribe it because they don't have a NP or a PA there, then go to Planned Parenthood.
However, I don't know if it would be free. If they are able to give it to you, it may be on a sliding scale.
I think it's amusing that the person before says to put on your big girl pants. I think she should take her own advice and learn to comprehend what she reads as you clearly understand the difference between the abortion pill and plan B (but then maybe she doesn't know that there is an abortion pill?). You are acting responsible by thinking over your options. Just make sure whatever choice you make is the choice you want to make.
If you cannot afford the 100 dollars for a pill, then I would hate to think about the cost of birthing a baby.