I have about 100 Hungarian books to sell. Does anyone know where I can do this? I live in Sydney.

Ebay? Amazon?

A larger university with a dept of Hungarian/Slavic Studies?

A Google search reveals there are several Hungarian social clubs in or near Sydney. There also appears to be a Hungarian meet-up group with more than a hundred members where you’ll likely be able to sell your books. Ideally you want to do a deal with a real person, face-to-face, to get the best possible price and to sell everything in a batch without having to pay shipping costs.