superbrightleds has a couple of PR LED bulbs.
PR2-1WHP-30V. Flange base 1 Watt High Power Cree XRE Cool White LED. 1 to 9 Volts DC and 7 to 30 Volts DC. 100 lumen.
I recommend the 7-30V as buck regulators are more efficient and probably brighter.
PR2-3WHP-9V. Flange base 3 Watt High Power Cool White LED. 3.5 to 9 Volts DC operating voltage range, 180 lumen. 110 degree beam pattern