There is also an option to buy standing tickets but they are sold only one hour before the show. If you feel you can stand for a few hours (with breaks :-) ), then this a great option too. They cost only €2(!) and offer great viewing position - specially the ones on the ground floor which are located ideally for great acoustics.
To get the tickets go to culturall.com. [update: the site is now available in English here]
It is basically, in German, but you should
- click on "Tickets jetzt buchen" and
- choose "staats oper" or any other opera.
- You will then see a list of all the performances for the upcoming month with the number of tickets still available for each price category.
- Once you know what you want. click on "Karten" in the specific performance area and
- choose "jetzt kaufen" (on the right, pink background) on the next screen.
- You will get a map of the auditorium.
- You can choose to see available tickets either by area of the opera (left) or by price category (right).
- Free places are marked with their seat numbers and colored according to their price category.
- Choose the seats you want and go all the way down and look for "Weiter zur Bezahlung" ("next to payment"). This will lead you to the payment process.
- You will then see the tickets you selected and their prices ("warenkorb" = "shopping cart").
- Choose "weiter zur bezahlung".
- You then have to create a user name in the site to be able to order the tickets.