Just this morning, a "Continuing Search" that I have going on eBay yielded two newly-posted ads with nearly identical headlines, and pictures of exactly the same item (different specific examples). Prices differed by a little over 10:1. Shipping on the more expensive one was "only" three times as high as for the cheaper one. Turned out that there were a lot of accessories with the one, justifying most of the difference.
I also found things like "vintage" drill bits advertised at $20 to $30 each, when brand new ones of similar quality (good ones, US made) go for $5 - $7. The pictures showed that the vintage ones were abused, with chewed-up shanks, burned tips, etc. One was visibly bent. For most of them, I wouldn't have paid a quarter, much less 100 times that much! The vendor had at least 20, each priced individually. Only a few listings gave the size, since the shanks had slipped in a chuck, and the information was obliterated. I'm much less knowledgeable about other stuff on her site (saccharinely sweet "collectibles", mostly), but pricing there looked like it might only be double what was reasonable.