I would cancel it and report her regardless, "Out of town" is no excuse. She bought it, she could have messaged you then. I have on several occasions waited until the end on ebay purchases and if nobody else was bidding or bought it, would buy now, and then message the seller and request time to pay (usually payday end of the week) as I didn't want to miss the opportunity. Every time, being honest and upfront, I have been alloted to the end of the weekend and always paid.
It wouldn't have been more than a minute to send a message while they still had internet and was logged in, to say, "Hey, I want it but will be out of town and out of touch, can I have until xx-xx-2013 to pay it. If not I understand and you can cancel/re-list it, I just didn't want to miss out on a good opportunity."
Not hard.
She's playing games, if she wants it that badly let her re-purchase it.
