Tesco BBQ Burger Grill Rack for 75p! Seems to be instore only, had loads in my local store. Barcode 051898039226.
I know I won't use it for another year but its a bargain at 75p!
Can also be used for sausages (or Sardines, like they do on beaches in Spain, apparently...) too.
P.S. Not recommended for swatting flies. The metal construction will probably cause more damage to your wall than to the buzzing insect!