As far as buying a new one, why not Fast Lane? Or Adsit. They are not expensive. I don't think you need any parts except the bulb housing assembly, which is basically one piece with a gasket - the gasket should come with it. Replacement is quite easy. It is hard to describe, but the plastic turn signal bulb housing assembly is just held in with a metal clip sort of thing that is part of the fender itself.

To get it out or in you squeeze a springy flap of metal, (part of the fender) kind of like trying to squeeze a "binder clip" for papers, and this releases the bulb assembly. It may be hard to see that flap of metal, the driver's side is easier than the passenger side, I think.

Maybe find an Indy shop to show you. Once you know how, it takes about 5 seconds to do it, but I could see that it wouldn't be easy to figure out. Only reason I know is that I replaced the whole fender on my 124 due to a deer hit.

Good luck,
Chris W.