Financial Dilemma

Last night I used a free pass to try out a pilates class. My dilemma isn't as obvious as it may seem between the title and first sentence of this post. I enjoyed the class, but realize that I'm probably going to need more in order to learn the basics and get the most out of the class. So after the class, I lined up with other participants with questions to ask the instructor how much class passes are. The woman in front of me was asking about a refund. She had just found out about a job transfer to another city, and had five classes left on her pass. Overhearing this, I offered to the instructor and the woman to simply buy her out of her remaining classes.

The instructor agreed to this suggestion, but here's where I'm not so sure. The woman who is moving told me that a 5-class pass costs $75, so I could simply give her $75 for the five remaining classes on her pass. However, after she left, it was my turn to inquire about the costs of passes, and I was told that a 5-class pass is $75, and a 10-class pass is $140.

So I'm wondering-- do I owe this woman $75 or $70 (half the price of a 10-class pass)? The way I see it, I'm doing her a favor and it would already be generous of me to simply reimburse her for what she can't use. But now she seems to want $75, giving her a $5 profit. I know that it's only $5, and I'm trying to just let it go. I haven't given her any money and plan on meeting with her on Monday.

As much as I try to let it go, I can't seem to think about what $5 could buy me. I could buy 2 gallons of gas, or lunch out during the week (instead of bringing my lunch).

I think that, for my own peace of mind, on Monday I need to offer her half of what she paid for half of the classes she purchased. If she doesn't like it, I could buy my own 10-class pass and leave her unreimbursed.

WWYD?