The Advanced Book Exchange is simply terrific, isn’t it? Search over thirteen thousand second-hand book sellers, and — more often than not, in my experience — you can find what you are looking for, and frequently at a decent price.
Of course, there’s a downside. Booksellers can now easily check on-line what is rare and what is not, and check what others are charging. It’s not that many years since I picked up the complete Principia Mathematica for £30: I can’t imagine a bookseller now being so ignorant of its true worth. Still, plenty of bargains are to be had: a copy of Wolfram Pohlers’ Proof Theory has just dropped through the door. I paid all of $5.95 plus postage.
It’s a bit disturbing, then, to read a paragraph in Private Eye which reports that abebooks have been hiking the commission they charge to booksellers and are about to add more charges. It would a great loss indeed if they price themselves out of having such a wide coverage of booksellers.