It does use a 14250 3.7V 250mAh battery.
Would these work I wonder?
1/2 AA R6 3.6Volt 1.2Ah Lithium Battery LS-14250 L14250 on eBay, also Other Single Use Batteries, Single Use Batteries, Batteries Battery Chargers, Consumer Electronics (end time 19-Apr-09 23:58:10 BST)
Ah, hang on...