I like the idea. I think this could be especially useful for people who find themselves needing to replace some unobtanium in old scopes or spectrum analyzers.
Also, I don't know how does it look like in germany, but in many countries vast majority of the parts are not availabe from retailers, and digikey/mouser/rs has prohibitively expensive shipping and handling.
I think that topic like "making large order from shop XYZ, who wsanna share s&h costs?" would be useful