Hi, we came over on a state sponsored visa in 2011, and as you have said your agent is right about the funds. You are required by SA to have $30,000 as a back up. You will get a form to fill in with all your assets that you believe you will have when it comes to moving to Oz. Now, to word this right, when we did this, we filled in the form to what we thought we would have..... (ticked all the boxes that were required) booked an appointment with a JP (justice of the peace at the local courthouse and he signed the forms and stamped them with an official stamp) and that was that. No proof required. So i will let you make up your own mind on that.
As for an agent been a rip off, i find that statement a bit harsh. Yes they are a bit pricey but if your busy with work like we always were, and two kids to put up with they are a god send. And they managed to get our visa in 6 months others who started their application at the same time as us were still trying to get there visa a year and a half later.
Goood luck