Hi Graham. There are so many things to check over that us amateurs will miss when buying a 'van. Chances are that it being 6 years old, all the faults have been fixed, but the slides might also be ready for some expensive work depending on the amount of use the 'van has had.

Depending on where you are in VIC, there are plenty of caravan repairers around who will inspect the 'van. Shop around for prices for you to take the 'van to them and for them to go to the 'van. Some repairers run a specialist service in pre-purchase of 'vans. Cost should be around $200-$300 tops and they will inspect it all and give you a written report.

Could save you a buying disaster, but good luck anyway !

Cheers
Bruce