Originally Posted by
luial
Is there any other possible way I can buy the tickets (from a third party)?
Sadly and frustratingly Munich is so scared of scalping that none of the trading/selling sites that are available is the US exist here, so you really have to go to the black market. I'm sure some enterprising people will stand around the entrance of the Olympic Stadium to sell you 5€ tickets for 20-30€ that evening.
Note that unless you get nice weather, the former olympic stadium is very uncomfortable since it was built for a summer event 40 years ago. You have zero rain protection and somehow the wind is sucked in badly. Enjoy the CL festival, and if the weather is bad, head for a bar.