Create a post entitled "What's my move?" on the WERA board. Is it meaningful stuff, or is it crap that, while annoying, could be easily replaced?
Bid on it and hopefully "win" the auction. It'll be funny when she realizes you know after she gets the ship to address. If you want, after you get it file a complaint with paypal and make her pay for you to ship it back.
I'm assuming it's something unique and valuable which is why you're posting. In that case, why not call the police and report it stolen (which it was). Then you can get it back pretty easily. Let her deal with it.
It's not the part... It's the whole bike it came from, along with the others. Frames probably went in the dumpster. Shady mother fuckers.