Footloose still sell them - they had them at Billing I think.
Its possible to get folding sand ladders, made from PSPs that are divided into three and then hinged. Still heavy but easier to stash. Im not sure how good they'd be.
Someone told me that the flexible mat things ruckle up under wheels in soft sand when power is applied (and so arent that effective); they havent got the longitidinal strength of sand ladders. Never used them though so I dunno.
'91 LR 110 Def/Disco hybrid "Elsa"
Bring me the horizon....