On eBay, user scatjazz04 sells a Becker hand [sale page link], advertising it as "rare antique late 19th century prosthetic articulated hand", further down advertising it as "very rare", demanding 1800 USD.
After this was posted, in the meantime, the item's description was changed to "early 20th century". Also that is not true, and it is definitely not rare or even very rare.
This is a Becker Lock grip hand, patented in the fourties of the 20th century (so not "early") and built to this day by the Becker family (hence the name). Its new price is 350 to 650 USD, used Becker hands never are worth more than a new one as they are not considered "antique" by any means. Why anyone would treat these as "late 19th century" items and ask horrendous prices is not clear.
Here are some images.
(C) copyright eBay / auctioneer