I keep on finding rare books for like pennies last year I was running early for work and I had some time to kill
so I had a wander around the town centre and the first charity shop I think it was a Mary Stevens shop I went into I found a 2nd edition of the Hitchhiker's guide to the galaxy for just £1.50 and the next shop just around the corner from it I found a proof edition of A heart shaped box by Joe Hill (Stephen King's son) for £1.25
But two years ago I found a English 1st edition of Richard Batchman's The rage for £1.15 and yes I told the lady at the till what it was but she didn't believe me and put the book back on the shelf without checking out it's value so the next day I went and brought it