Thorfire 2x18650 headlamp, apparent clone of Fenix HP30. $6.73 (used, Very Good condition) at Amazon. Select Amazon Warehouse Deals from other / used sellers. https://smile.amazon.com/gp/aw/d/B01610DW16
Edit: discussion thread here:Thorfire 2x18650 headlamp, similar to Fenix HP30, for <$7 (UPDATE: Now with reviews and pics)