Dale
I don't know any local Queensland companies. But I went with a Ranbuild shed this year and the process, delivery, and construction were pretty much faultless. Very happy with the quality and instructions. Certainly not the cheapest, I went with a deluxe model which has few more flashings and colored screws, they do have a cheaper range.
If I could offer a couple of suggestions for any shed.
Insulation, I went with wool over Aircell at the recommendation of a swagger. Saved a heap and it is working out really well. I feel Aircell is preferred because of easier installation costs, but if you read the specs it only works efficiently with an air gap which is hard to maintain between rafters.
Sheeting, went with thicker cladding only up one size and cost very little more. Make sure you compare the cladding thickness between brands.
Uprights, if I was doing it again I would spec heavier columns. The standard ones on my shed are very thin and twist easy compared to say the thickness used for roller door mullions.
Rafters I added an extra rafter and closed up the distance between them from 1100mm to 800mm again added SFA (I just purchased the top hat section and extra screws) and if you have to walk on the roof it makes a world of difference. But will also pretty much make Aircell inefficient (see above)
Roller doors, get good ones. All domestic doors are light pieces of crap today.
Good luck, its a great size shed you are proposing.