If this is the shop I think it is, in Oakland, then I got the last one in the display case, along with a set of Mafac "Racer"s. (That's how I type it, 'cuz it's funner that way.) Along with a bunch of other parts and bits as I've tuned the Probable Peugeot PKN-10 to my needs and wants. If the rules of the list allow, I'll post their full contact info, because people should buy stuff from them and give them money, because they're righteous dudes and they deserve it.
As to the racks themselves, they really do only work with Mafacs. "Racer"s are what they were made for, and I've seen photo evidence that the work on Raids, as well. They're known to not work on Weinmann / Dia Compe centerpulls without modifying the rack a bit, which I can at least partially confirm, as last night's attempt ended in ignominious failure. They were made to sit under a decaleur'd handlebar bag, where the decaleur carries a lot of the load. Using them for basket duty tends to break 'em.
Anywho, that's what I know about them. And, if the list allows, I'll shamelessly promote the shop in question, if it's the one I think it is.
--Shannon