Welcome Jono,
http://www.andrewscom.com.au/site-section-10.htm
is a great place to start and I would recommend going and seeing these guy and
http://www.bintelshop.com.au/ and
http://myastroshop.com.au/
Firstly what are your expectations. Are you looking for massive views of planets, or big galaxies? Do you want to take top quality pictures.
Generally the above scenarios are many $$$ 10,000 plus all the rest
The Guan Sheng GS-680-LTD
$399.00 AUD is a great start to get as much light into your eye for the $ you spend. TO make it up to $500, you could get say a 9mm or 12mm eyepieces for looking at things closer and a 20 or 25mm eyepiece for wider views.
Janokiss has a 8" and I know he is happy with it.
Keep asking away and don't rush in!!
Or for $599 you are into a 10" dob.
The 8" dob is very portable however.
Lots of guys in sydney that can help you choose. There are get togethers, so you can try before you buy.