Purchasing NOS or used is not so black and white in my experience and probably those of many others. My vintage bikes are all riders. I've purchased NOS parts many times to use if they are wear parts and I am willing to pay a bit more to be assured of their condition. NOS parts offer TRUE value. When you purchase some used bike parts, you're taking a chance on their value. Headsets, chainrings, bottom brackets and axles, sure, people tend to offer photos of the races and bearing surfaces or chainring wear, and so you know what you're getting. Pedals, hubs, freewheels, people don't offer photos of the bearing races. You gamble on their value if used, and you may lose in the long run and have done better purchasing NOS. Vintage NOS chains, yes, I prefer to pay more for an unused chain than purchasing used vintage chains.
Peter Brueggeman
La Jolla California USA
4peebee(at)peterbrueggeman.com