Godaddy are cheap because they sell lots of them. They are just as valid and secure as others and work on all browsers. I like the godday option of being able to run multiple domains from one SSL. So you can run both domain.com.au and domain.net.au under one SSL.
At the end of the day most users wouldn't know the difference between SSL keys and are only concerned that the site is secure. 256 bit encryption is the same either way.
Cheap Geotrust and in USD
http://www.opensrs.com/services/ssl/geotrust
Lemon