It sounds to me like she is making an excuse, either she wants more money or has found someone else to sell it to. She should come up with a better lie, you list "but it now" when putting the item up for sale and it is all easy to do.....you can't really stuff it up. Once it's up for sale it's up for sale, she would know that.

That being said, have you paid? She has the item still, she doesn't have to give it to you. She will have to be prepared to receive negative feedback and my get banned for a bit or just receive negative points and feedback. But at the end of the day she doesn't have to give it to you IYKWIM (even though she should).

Ahhhh bummer really!