Rather interesting that the Cygolite 320 Dash pictured in Bulgdog's pictures is identical to the $30 Blitzu Gator and the $10.42 model I listed above in my post with the exception of minor differences in the plastic housing. The specs are identical. It has now been replaced by a $40 Dash 350 which has 4 smaller LEDs in addition to the main one.
If you don't like dealing with the external battery pack which is really necessary for very bright lights pulling a couple of watts, go with the single CREE XML-T6 flashlight. The output is 1000 lumens (according to CREE) and you can zoom the light if needed to get different lighting patterns. It runs on a single 18650 Li-ion battery (3.7V, 4200 mAh) that you can switch out in a few seconds and which is small and light enough so that you could carry a spare battery if you were concerned about running out of juice. The flashlight will operate for several hours on high or many more in flashing mode. Many sellers in the US charge less than $6 postpaid for just the flashlight USA Stock CREE XML T6 LED 5000LUMENS 3MODES 18650 Zoomable Focus Flashlight Lamp | eBay You can get a pair of them with two batteries and two simple chargers for $11 postpaid 2sets Tactical CREE 5000LM Led Flashlight Torch Zoom Light+18650 Battery+Charger No matter what is advertised, the output for the CREE emitter maxes out at 1000 lumens. One of the best mounts for a flashlight is this 360 degree rotation handlebar mount. Sells for $4.69 from a US seller or just a buck from overseas sellers $.99 postpaid 360 Degree Bike Bicycle LED Flashlight Mount Holder Bicycle Torch Clip Clamp