A possibility to eat inexpensively is offered by the cafeterias (Mensen), which are situated around the main building on the Universitätsring as well as close to several institutes. The cafeterias and buffets are run by the so called Österreichische Mensen Betriebsgesellschaft mbH.
Everybody can access the cafeterias, no ID is needed. In order to make use of the offer even more reasonably, you can obtain the so called "Mensenpickerl" of the students' union. You will receive the Mensenpickerl at the student's union with your student ID. With it, you benefit form a € 0,50 reduction on each Mensen-menu.
Apart from the cafeterias (Mensen), you will find many cafés and restaurants next to the main building of the University of Vienna , which are popular with students and which also offer low priced lunch menus and snacks.