Walkers 'clash of the comics' crisps at poundland - Probably not the cheapest I know - but haven't seen the anywhere else (although I'm sure someone will correct me!)
Flavours available are -
Stephen Fry Up - Full english breakfast
Frank Roast Dinner - Roast chicken dinner
Jimmy con Carne - Chilli con carne
Steak & Al Pie - Steak & ale pie
The comics are in competition to sell the most of their flavour - the loser to do a forfeit for comic relief.