Yikes! Welcome to the Wild West.
Caveat Emptor

A bit offtopic, but what places beside eBay are there to find vintage chess sets? I usually look through eBay, local craigslist, etc., but rarely come up with anything interesting.

A bit offtopic, but what places beside eBay are there to find vintage chess sets? I usually look through eBay, local craigslist, etc., but rarely come up with anything interesting.
https://www.antiquechessshop.com/
A bit offtopic, but what places beside eBay are there to find vintage chess sets? I usually look through eBay, local craigslist, etc., but rarely come up with anything interesting.
I agree that Etsy is a good non-auction place to look, particularly for used, Soviet-style sets. There is also catawiki.com, which is sort of a European eBay, and liveauctioneers.com, which pulls together a lot of auction sites for all kinds of objects, including chess sets. Just do a search on either of those...but caveat emptor. ;-)
House of Staunton has an antique and collectibles page: https://chessantiques.com/product-category/chess-antiques/
There are some interesting old sets for sale at: https://finerpieces.com/
Alan Power refurbishes and sells old and collectible sets here: https://www.thechessschach.com/
And here is a page with a few more links you might find interesting: https://www.chessantiquesonline.com/UsefulLinks.html
There are a lot more out there, but these are the ones I've spent the most time on browsing and fantasizing. Have fun...
Last month I was surfing around on various web sites looking at old chess sets for sale. I noticed a pretty looking set that was offered on an auction web site (not eBay) that was listed as a 1795 Calvert chess set with a box that was both a board and storage. Here are pictures of the item:
I thought the whole thing was in remarkable shape for something over 200 years old, and I started to research it. What may be obvious to most of you is that this was a reproduction set, and, as far as I could determine, many of these were imported from Hong Kong and sold at various game and gift sites around the U.S. starting a couple of decades ago. I alerted the web site where it was on auction prior to the close that this was being deceptively advertised and that this was a reproduction with plastic pieces. I even sent them half a dozen links to document other places where it was offered new and used. This is a web site that has resident experts who review the listings and they said that they believed that this was an authentic antique set. I followed the auction and someone ended up paying about $840 for this set including fees and shipping. To top it all off, I even found this same set had gone for 20 euros on the same web site 2 years previously, where it was honestly identified as a reproduction with plastic pieces, and supposedly vetted by the same expert. I think it's a rather well-done repro, but that someone ended up paying $840 for something like this is sad and mind-boggling.