And the best ones around here are invariably for charities I've never heard of.
There's the Shop with the Scary Ladies; we are all too intimidated to leave donations here in case we fail to meet their exacting standards.
There's the Cheap Charity Shop a few doors further down the road; not as cheap as it used to be since they cottoned on that dealers were buying from them, but still cheapest by far for books.
And that's where I found a copy of Proust yesterday - Swann's Way, the first volume of Á la recherche du temps perdu - for 20p.
I've been promising myself that I'd try this again ever since I finished The Hare with Amber Eyes and realised that Charles Ephrussi was a model for Swann.
I haven't read Proust since I was a student and fancied the idea of myself as a cultured young lady who read very long books. And I got through this first volume (and quite a lot of Ulysses, and nearly all of War and Peace) and can't remember very much about any of them.
That 20p bargain shouted to me that this was the time ...
But am I ready to dunk my madeleine into my tisane - or even my KitKat into my mug of Yorkshire Brew - whilst reading a paperback that seems to have been kippered in a home where its previous owner smoked like a chimney? (Funny how you never notice a book's musty smell before you get it home.)
Maybe I should have waited for a more salubrious copy?
Or can I sip that tisane while holding my nose?