Household central built in ducted vacuum cleaner system 50mm PVC coupler for joining ducting together. It fits over both pipes.
Vacuum pipe is a different class to retic pipe, plumbing pipe or waste pipe, so they won't fit together for safety reasons.
As it's light, maximise the saving on postage and buy some of the related parts below, such as dustbags and the filters or a new floor tool.
At the moment, standard postage within Australia is capped at a maximum of $20!
We at TVD carry out in-home repairs on built-in ducted vacuum systems in the Perth area from $135, call 08 9362 6044