These are small rugged headlamps designed for caving, hunting, hiking/bushwalking and tough outdoor activities.  They are waterproof and will shrug off mud, pressure washing, cold, heat and an impressive amount of assorted abuse.  Powered by a single rechargeable 18650 battery (designed for unprotected, will fit some but not all protected).  Battery and charger sold separately.   Model: H600d Mk IV High CRI Neutral White 18650 Headlamp

I've tried other cheapie options, a few came close but none lived up to the Zebralight. 

Many features, including great brightness on high, long burntime on low, light weight and battery indication without having to take it off. Suitable as a backup light or primary light for any level of caver (lightweight cavers use them on major expeditions).  It doesn't have a charge port (extra weight/failure point) or a magnet (compass/navigation interference).

Generally in stock in Melbourne, Australia.  Shipping worldwide should be reasonably economical.