I love leather saddles and I almost always buy them used. Used ones look better, are more comfortable and are cheaper. I generally pay €20 - €50, depending on condition, at swap meets and online. The trick, I find, is to keep an eye out and buy them whenever they come up for sale, and not wait until you actually need them.
My favorite is probably this well-used Brooks Pro which came off a €60 donor bike ten years ago, and has been on various L'Eroica bikes since then. It has just the right color, shape and wear for me:
The only exceptions are the B17S Imperials mrs non-fixie has come to love. I've not been able to find them used so far, but at ~ €90 new, I think they're a pretty good investment.Come to think of it, buying anything mrs non-fixie likes has turned out to be a pretty good investment.