As I got told it is indeed sold out since weeks. The business lounges for example been sold out two weeks after it was sure Frankfurt will host the final.

Only chances left are, you know someone with free tickets (a company for example) or try to get some on the black market in front of the stadium.

My friend said the tickets started from more than 100 Euros up. I am sure they won't be cheap in front of the stadium.

Pit