I would suspect that it's cheaper to ship your belongs rather than buy all new stuff here. You mentioned $7600 USD which is about $10,700 Australian at the moment. When we moved here from Canada we didn't ship anything so we had to buy everything new (except clothes). We spent about $15,000 to furnish our place using relatively inexpensive things. We do have nice living room furniture but the bedrooms and day to day items were fairly cheap. You'd be surprised how quickly things add up.
I would suggest making a list of all the items that you would need to be. You really have to walk room to room and write down all the things you have in it. I really do mean all the little things too. The furniture is obvious, but it's the little things like office supplies, kitchen utensils and toys that really add up. Once you have your list work out how much it would cost to replace all that, I used the IKEA online catalogue as a cheap price guide. I would also work out a list of how much you estimate you would get if you sold all your furniture you have there (you probably won't get as much as you think). Remember to also look at what you have outside (furniture, BBQ, yard equipment).
In your case just furnishing a bedroom (bed $300, mattresses $400, linen $100, dresser $200) would probably cost about $1000 per bedroom if you're not buying expensive stuff.
So unless you've got really crap furniture now and would like to start over than you're probably better off
shipping it. We didn't ship because it was way more expensive (from Canada) and we had a lot of crappy things from our university days. If you can't fit everything into a container just sell off/get rid of the items that take up the most space and are not to bad to replace.
As far as Mackay goes I have no idea. I would suggest having a look on this forum to see:
http://britishexpats.com/forum/forumdisplay.php?f=54That forum has a lot of people from the
UK moving over but there are also people from all over. There's lots of people to get advice from and I know there's a few in mackay who can answer questions.