I decided to finally put some insulation under the floor (last few nights were really cold in Perth), probably XPS boards, something like this: www.expol.com.au. Not sure yet if that is available in Perth as I can only see it being sold over east, I guess they will be able to ship over?
Anyway, I wanted to check if anybody knows where I could get XPS sheets, at least 50 mm thick, 500 mm wide, length does not matter, the longer the better.
Will need enough to cover about 120 m2 at reasonable price.

PS: I also considered insulation batts and foils and I'm leaning towards XPS, any feedback on other options is welcome. I have good access under the floor, the beams are steel with wooden floorboards on top.

Thanks

Foamsales.com.au

The lads down there will help ya out, at booragoon, surprised there's no environmentally friendly version of xps insulation yet, stuff works well summer and winter

^^^ agreed, their prices are good and they are helpful. I bought Delrin underfloor sheets there for another project and they were tops.
Unlike the big yellow building nearby.......

R3.5 or r4 bats with aircell stapled with foil fasteners to underside of joists, a 30 mm clout in the hole of the foil fastener gives a stong fix, gives great insulation value, use this method on any framed above ground houses, never had a bitch from any clients regarding cold floors