Environmentally friendly businesses may be the perfect bootstrapped startup because they have a natural niche from which to build a customer base.

Consider Brilliant Earth, a business built around conflict free diamonds and renewed gold. Read more.

In this interview with Leah Edwards at Ecopreneurist, Brilliant Earth co-founder Beth Gerstein explains how the company was founded with little capital investment.

Additional thoughts on bootstrapping environmentally responsible of other ethically responsible products:
• Focus on selling. Many products from free range non-factory farmed meats to fair trade products are already available somewhere in the world. Focus your efforts on connecting buyers with sellers as Brilliant Earth did rather than on capital-intense production.
• Educate don't advertise. Customers for ethically or environmentally responsible products will seek out and even pay extra for what they value as long as they know where to look and new customers can be developed simply by educating them about that value.
• Cash first is key. Finding customers first instead of purchasing inventory was a major part of Gerstein and Grossberg's business model and a major departure from the industry they were entering, but the approach replaced costly risk with hard work.
• Raise awareness. Peter Thum, founder of ethos water, which was bought by Starbucks in 2005, found that donating portions of his company's proceeds to clean-water initiatives in impoverished communities worldwide was a natural selling point.
• Seek volunteers. Your higher ethical values may attract those passionate about your product, something Shelli Styles founder of Strappity-do-da, a company helping to raise women out of poverty in Columbia, found gave her a volunteer sales force in the early days.

Read more of Shelli's story in this full length article from BootStrapMe.com.