I have a problem with eBay buyer...what should I do?

K, I listed a ton of items that I have been collecting over the years. I am selling them fairly cheap mbecause I need the money right? So this buyer bids on an item, after 3 days the bid is up and she wins. After a day I send her the invoice. Two days later she emails me and says "my cell phone blitzed and made the bid for me; I don't really want it. Sorry". Well, I'm a little ticked off and I want to get paid. Can I make her pay for it and can she nail me with a negative feedback? I don't want to cancel- I put stuff on there to sell and get paid. So is it wrong to want to get paid?