£20?
I’d hit ebay and search for an XML torch of some sort, and some reasonable 18650 batteries…
Although if it’s for the lid, I’d suggest a separate single LED Bastid type light with the battery in your back pocket/Camelbak to keep the weight off your head/neck, not very joystick like but having strapped a 1x 18650 type torch to my lid before, it’s bearable for a while, but after a few hours it does affect your neck muscles, how long are your night rides typically?
battery & charger* included / UK seller / free postage / £13.98
Can’t say fairer than that…
(*might burn your home to the ground)…