Salzburg is a very touristic city with tons of hotels in different categories. You will find your way in online booking services like Trivago (http://www.trivago.de).
Our recommendations (close to the venues):
http://www.yoho.at
http://www.gt-hotel-salzburg.com
http://www.trumer-stube.at (Update: Ausgebucht!)
https://www.motel-one.com/de/hotels/salzburg/hotel-salzburg-mirabell
or near Radiofabrik:
http://www.jufa.eu/jufa-salzburg-city/
Guys on budget can also apply for CM-Couchsurfing