These guys own a big chunk of the world hair market: http://www.zimbio.com/TTD/articles/16/Hair+offering+at+tirup... . As long as superstition and India's population remain stable, at least supply shouldn't be a problem :)
One man's religion is another man's superstition, I guess! And shaving off the hair is pretty harmless, as "superstitions" go -I mean, I got a lot of friends pretty non-superstitious types who shave off their hair here in the valley.