I've flown at the Melton Flying school before and currently flying at Essendon and there's a big difference in the costs. If I remember correctly, it was less than $100 to hire a 152 solo at Melton.
Here's their
website for further details.
The CFI there is also the LAME and fuel is available at the field. It's also not too far from Avalon so if you're wanting to do IFR training you won't have far to fly to get to the navaids.
As for schools at Essendon, there are three to choose from in the main terminal building; the one in the middle of terminal building charges fuel at an hourly rate on top of the normal hire rate of the aircraft which I thought was quite odd (although I stand to be corrected on this, but I think that's how it was explained to me).