old and rare book shopping

For the past year I have been collecting old physics books and I'm looking to expand my collection as well as starting my maths book collection. Does anyone know where I can buy these cheaply? Any particular bookstores or charity shops? Thanks!

For the past year I have been collecting old physics books and I'm looking to expand my collection as well as starting my maths book collection. Does anyone know where I can buy these cheaply? Any particular bookstores or charity shops? Thanks!

Idk if it might be worth contacting local universities especially if they have a physics department. My uni had regular clear outs during term time and whilst it wasn't a physics department there was often a 'free to a good home' pile in the department building of old textbooks/research books. There was even a 'how to use windows 95' book in that pile!
If you explained you were collecting and offer to pay for some of their old textbooks they might be amenable but it's hard to say (could be worth enquiring though).

For the past year I have been collecting old physics books and I'm looking to expand my collection as well as starting my maths book collection. Does anyone know where I can buy these cheaply? Any particular bookstores or charity shops? Thanks!