I had noticed about $20-25 on eBay but they were usually not in the best shape. I'm happy with it, especially since Plomb is scarce here in Ohio.
I also won another auction for a NOS Plomb keychain screwdriver in much the same manner. It was listed as Plumb, grainy low-res pix. It is the black oxided finish, and the rear side is blank. That one was a straight auction, found right after listing and starting bid $9. I bid $10, waited 7 days, and no other bidders so I won.
There are a number of legit complaints about ebay but it's fun if you are patient.