Nilfisk
Nilfisk BV1100 Commercial Backpack Vacuum Cleaner Cloth Filter Bag
Nilfisk BV1100 and the Nilfisk-ALTO Powervac and Origin and Pullman and Hako Rocketvac commercial backpack vacuum cleaners fabric main filter and cloth dustbag.
It can also be used without paper dustbags, but by using the paper dustbags, it will last a lot longer as well as being healthier to handle and easier to dispose of the dust, See them HERE
As they're light, maximise the saving on postage and buy some of the related parts below, such as the filterbags and the filters or a new floor tool.
At the moment, standard postage within Australia is capped at a maximum of $20!