1/150? Wussies! The Friedrichshafen Zeppelin Museum has 1/66th-scale models of the H´Burg and the Macon, the latter complete with Sparrowhawk fighters! And a horde of other Zeps in the same scale. Awesome display.
However, if you consider the amount of work that must have gone into a piece of that quality (judging from the pics), 500 Euros is rather fair price, considering what ship models of similar size fetch these days...
Collectors market. I wonder, though, how this made it to E-bay.