Lost personal property--now up for auction..Please Advise

A bike part that I inadvertently left out in my driveway 2 weeks ago,
has now appeared as an auction listing on eBay, by a seller in the same
town as me (no surprise). I am 100% positive it's mine due to
excellent pics that show a Sharpie-inscribed number among other
noticable details, etc.

What's the best strategy to try and recover it?

Thanks in advance.

.

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