Yes bookfinder.com is great. For French books I also like https://www.chasse-aux-livres.fr/ https://www.chasse-aux-livres.fr/ which also search in some local fr

Yes bookfinder.com is great. For French books I also like https://www.chasse-aux-livres.fr/ https://www.chasse-aux-livres.fr/ which also search in some local french websites for used books.