I would imagine most caravan shops would be able to fix you up, i dont know the type on your van but most are standard sizes if not it may be possible to increase the opening to suit a newer design, as for s/hand ones from the breakers i would expect them to be aged and brittle as they get direct sunlight on them, i lost one on my van last year all that was left was the handles the heads of the screws had rusted through, the new one has washers and stainless screws hope this is some help.