It's quite a big niche:http://en.wikipedia.org/wiki/Demographics_of_Islam
"There is a considerable discrepancy between the Muslim total derived from adding up the figures for the various countries (1,363,000,000) and the Muslim total given by the CIA World Factbook (1,283,000,000). The CIA estimates that Muslims constitute some 19.9% of the world population. If the larger figure is used, the percentage would be 21.1%."
Don't underestimate the market for religiously based fads - for all we know, these people may have found a goldmine.