Conveyor belt is the go
it's tough, thick and reinforced with layers of fabric. ( ours have been fitted for the best part of 10 years and are going strong even after 1000's of km off road ).
I've never had to buy it
, but you could Google it for sellers in the Brisbane area
or ring around a few quarries, concrete plants, asphalt plants etc to see if they have any old /used offcuts lying around that they would part with for a box of gold or similar !! The worst they can do is say no
Cheers
John K