I think you're right.
From a swissramble blog (http://swissramble.blogspot.no/2012/10/borussia-dortmund-back-in-game.html):
Deloitte league 10/11, before the CL money started rolling in as a result of what Klopp had achieved:
Schalke might have some CL money in that, I'm not sure. Either way it goes towards showing that it's not like Dortmund have been comfortably the 2nd richest club in Germany all along. Unsurprisingly those financial results have come as a result of success on the pitch.
This is purely income and income does not equate to wealth without taking expenditure in to account.
You can add vfl Wolfsburg in to the mix in the "rich list" bearing in mind they are fully owned by VW.