Maxi-Car hubs aren't made any longer. Production stopped about 4 years ago. Not only that, unlike Campy, there appear to be no stocks left at wholesalers. They always were very expensive (take one apart, and you see why: Special bearings, triple labyrinth seals, a lot of machining, etc. - cost was no object when making these). As a result, few dealers stocked them, prefering to special-order directly from the factory. So once the company sold out their stocks, they were gone. I know the Alex Singer shop desperately is trying to find some, because they need them for their bikes...
I have been looking for Maxi-Car hubs for over a year and a half now, and I found a few sets for my personal consumption. I have for sale:
2 sets of Maxi-Car hubs, large flange, 36 holes, NOS, slight shopwear (would polish out easily if for display, and wouldn't be visible on the bike). BSC freewheel threads, heavy-duty version (no holes in the flanges and slightly thicker front axle which still fits in standard dropouts - otherwise same as standard), as follows:
1 set for quick release, 130 mm rear spacing, no skewers (Singer and Herse usually used Campy NR anyhow), $ 395 shipped in the U.S.
1 set of 36 hole solid axle, 135 mm spacing, for wingnuts (come with track-style nuts), $ 375 shipped in the U.S.
The prices reflect their scarcity - it appears a lot of desperate cyclotourists are trying to stock up while they can. After this, I am afraid that there will be no more. And as you have seen, used sets go for more on e-bay!
Spacing on these hubs is easy to change - if you need 126 mm, that can be done. 120 is a bit more difficult...
Jan Heine, Seattle