I compiled some data from MTBR on their 2012 bike light shootout.
I will let you make of it what you will. The sorting is by $/Lux. Lux is the total brightness in one area (spot mode) and the lumens are claimed. See the MTBR review for detailed information: http://reviews.mtbr.com/2012-bike-lights-shootout
Speadsheet with data: