Go here:
http://resolutioncentre.ebay.ca/
and start an Unpaid Item Dispute on Day 4 (96 hours). Close after another 96 hours.
You will get your selling fees back. She will get an Unpaid Item Dispute strike, which will make it harder for her to bid on eBay in future, with anyone. Neither of you will be able to leave feedback. She will not be able to leave Detailed Seller Ratings.
To prevent this in future, go to your Seller Preferences and Block automatically bidders with UID strikes, bidders without active Paypal accounts, and if you are using Fixed Price listings, require Immediate Payment with purchase.