My skinflint powers have been defeated & I've actually put my hand into my pocket and took the screws out of my wallet...
"Oh sh*t. We've been decimalised!"
There I was in B&Q on Saturday, a place with all the calm dignity of a poorly run refuge camp, to purchase (aaaaaaagh - the pain) a roll of black plastic.
A bit later; two new beds dug, both covered in shiney new plastic and a 5 meter wide DMZ of more black plastic between the pumpkin-zone-of-control and the green menace (docks, nettles & other ner-do-wells).
I can't get to the plot often enough to keep the weeds down if I've dug anything over, so this seems to be my only option. I know it's not very nice environmentally, but it will be reused.
Hell. If I have my way it'll become a bloody family heirloom!