Quantity   Component name
1 × A smidgen of solder and some heatshrink. To keep it all neat and presentable.
1 × Bulb holder - assuming you can't reuse the existing one Search for Socket Xenon LED Light Bulb Car Truck Connector Extension S25 1157/BAY15D MPH
1 × LED headlight bulb - BAY-15D 12V - the brighter the better - within reason. Search for 1157 BAY15D 18 LED SMD 5050 Car Brake Turn Signal Light Bulb Lamp Pure White 12V
1 × Holder for the above. (or modfiy the existing holder for more hacker points)
1 × LED PWM Controller Search for 1pcs White portable Min Single Color Dimmer For 3528/5050 LED Light/Strip
1 × Wall Wart - 12V enough amps for the bulb.