The gas canisters are on a 3 for 2 at halfords - as are the cookers themselves. I don't suppose you have a need for 3 cookers - but i'm going to give them to friends.
At 1.50 each, on a 3-for-2 that comes to 1 pound per gas canister.
http://www.halfords.com/camping-car-seats/camping-caravanning/cooking-dining-equipment/halfords-bright-spark-camping-gas
At 10 pounds each, on a 3-for-2 it comes to 6.67 per cooker.
http://www.halfords.com/camping-car-seats/camping-caravanning/cooking-dining-equipment/halfords-portable-gas-stove
If you want something larger, and stronger - i got one of these, but it needs a large propane or butane bottle:
http://www.ebay.co.uk/itm/LARGE-BOILING-RING-CAMPING-LPG-GAS-STOVE-BURNER-COOKER-CATERING-PROPANE-BUTANE-/161356254615
At 1.50 each, on a 3-for-2 that comes to 1 pound per gas canister.
http://www.halfords.com/camping-car-seats/camping-caravanning/cooking-dining-equipment/halfords-bright-spark-camping-gas
At 10 pounds each, on a 3-for-2 it comes to 6.67 per cooker.
http://www.halfords.com/camping-car-seats/camping-caravanning/cooking-dining-equipment/halfords-portable-gas-stove
If you want something larger, and stronger - i got one of these, but it needs a large propane or butane bottle:
http://www.ebay.co.uk/itm/LARGE-BOILING-RING-CAMPING-LPG-GAS-STOVE-BURNER-COOKER-CATERING-PROPANE-BUTANE-/161356254615

Anyone know where you can get those giant Karahis or Tawas in the UK?
but great to watch