Avoid Dodo like the plague - horrible service. I work in the ISP industry, just trust me. Run as far away as possible from them. Avoid Vodaphone as well - their customer service (ISP side) is shocking - I've heard many customers complaining of 2-3 hour waits for someone to answer the technical support phones and then some.
My ISP (ECN Internet -
www.ecn.net.au) offers Wireless 3G (Optus back end). If you get good mobile phone reception with Optus, the chances are that Wireless will be fine. I can't remember the pricing to be honest (I'm a techie, not a salesperson). It seems that there's no PDF up on our website (must fix on Monday) for our Wireless plans. I'll provide a link when I've fixed it, so you can check out prices etc.
Dave