The bar clamp holders also take a MTE SSC P7 torch. You have to mount them in reverse so the clamp end clamps up on the on / off switch on the P7 , as its a few mm fatter than the midsection . This does mean the torch is central over the bars so should be a tad more wobble / nose dive resistant.
I have the purple ronnie one, its OK in a Tesco torch kinda way .
However with the £ / $ rate these P7 Ultrafires from DX come in at £14.00
http://www.dealextreme.com/details.dx/sku.36356
Buy 3 for £42 , get smudge to make up a cell pack for 2 on the bars and keep 1 with an 18650 on your lid . More light than neccessary , with redundancy for what ~ £60. Manufacturer rated 2700 lumens , reality rated 1500 lumens.