I found this shopping list on the candlepower forum, who'd taken it from a customer review on dealextreme, so thanks, whoever you are. In short, its not my idea, although I've brought some of the bits together, but its excellent and inexpensive from dealextreme.
Start with a boggo, 250 lumens, WF501B, SKU 16240 $13.01, plus a 26.5mm aluminium reflector, SKU5955 $2.76, then a 28mm aspheric lens, SKU5297 $1.92
Unscrew the top off the torch, wind out the lens retention ring with a pair of pointed tweezers or needle nose pliers and replace the lens, unscrew the reflector from the LED and spri