I gotta say I've got my little hoard of cool NOS parts, some of them worth a fair bit. I acquire these sometimes with a long range view for a project a few years off. Sometimes then, when it comes around to using them, I just can't bring myself to do it and buy a slightly used part instead. My little neurosis, but it is a good way to build up a stash over time.
If you are in Tokyo, check out Setagaya Hasegawa Jitensha, this is probably the best old parts shop in all of Japan. No website or anything, just an old guy with his parts and a wife who serves tea to the customers.