Austria has some of the cheapest voice and data plans in the world. You can walk into any electronics or mobile phone operator store and get a prepaid sim card for 10 to 15 Euros which will already include airtime and data. There are also prepaid iPad/etc. data plans that come with a micro/nano sim card. Rates and offered plans change frequently so it's best to check the websites of the providers prior to traveling to Austria.

These are some current (02/2014) links for the provider's prepaid packages:

http://www.drei.at/portal/de/privat/...e/startpakete/

http://www.a1.net/handys-telefonie/bfree-wertkate-plus

http://www.t-mobile.at/handytarife/wertkarte/index.php

Some supermarket chains (Hofer, Spar, ...) have their own prepaid plans as well and piggyback on the big provider's networks.