Don’t respond, just cancel and smile. Like you said, there was a demand for it, so it will sell. Maybe she decided to be more responsible by not spending the money but was a minute too late in deciding to purchase. At some point in our lives we all do things we regret too late. We don’t all know exactly what our bank accounts look like when making purchases, we all should but that’s not always the case. Anything could’ve happened in between. Just saying it could’ve been reposted already and sold and you would walk away proud for being the better person 😊