The examples of niche businesses at the end remind of a another niche example from Tim Ferriss's 4 Hour Work Week (paraphrased):
> A man created a low-budget how-to DVD for less than $200 and sold it to owners of storage facilities who wanted to install security systems. It’s hard to get more niche than that. In 2001 selling DVDs that cost $2.10 to duplicate for $95 a piece through trade magazines, he made several hundred thousand dollars with no employees.
> A man created a low-budget how-to DVD for less than $200 and sold it to owners of storage facilities who wanted to install security systems. It’s hard to get more niche than that. In 2001 selling DVDs that cost $2.10 to duplicate for $95 a piece through trade magazines, he made several hundred thousand dollars with no employees.