Actually you are right and wrong.its easy, theres no money coming in.
The German Bundesliga generates more sponsorship money than the EPL and has the heighest average attendance of any league in Europe.
So there IS money, but the clubs are not competing with the top leagues, because they are clubs.
In Germany clubs are really that - clubs.
They answer to their 'members' - the fans and if you rack up a whole lot of debt, you won't get re-elected or you get docked points.
Also, there is a limit to ticket prices, which limits the clubs' incomes.
Several German club directors have known for years that Spanish clubs are in big big trouble.
So the money is there, but they are not going to become suicidal like the Spanish clubs just to compete.
They';re managing their clubs sensibly and when this current bubble bursts and prices as well as wages becomes normal again, they'll go shopping.
The other factor is a lack of young German talent.
There are some good players coming through to bolster the ranks of the National team, but not enough good players to negate the need for foreign talent.