I used to buy chain on line, now I buy it at the local co op. They sell new consumables at their cost, and it gives me an excuse to stop in and donate some stuff (and maybe pick up some stuff too).

All of my bikes are vintage, newest is 1990, most are quite a bit older than that. So I tend to pick up used parts for most needs, other than consumables. One consumable I will pick up used are tires.

I continue to find nice vintage parts in the form of a complete bike, at a reasonable price. This is the latest example: Suntour barcons, Suntour Vx GT RD, swiss threaded BB, french headset and french stem, 5 speed freewheel., decent Tourney crankset, nice Weinmann center pull brakes. Most just see a low end Motobecane with handlebars in DUI orientation. I see a ton of super clean parts and no rust.