Caravanland sell inner spring mattresses for the Swan etc that are made locally in Perth, by SlumberKing for memory. Given they are locally sourced and made to size it means you aren't paying freight from over east like you would if you bought the "Jayco" ones. We found the locally made mattress really comfy when we had our Swan. Given they get those made to order, I am sure they could probably source them for an Expanda too. Worth ringing the Toy Shop there and asking.