The entire company follows the philosophy of reduce, reuse, recycle—from the fertilizer, to the used and donated 20-ounce bottles in which the product is packaged, all the way down to the computer systems.

"Since the whole company is focused around doing things with waste, we decided to find old computers that no one else was interested in and put those to use," says Beyer. The two visited the Princeton surplus department, where they found a plethora of computers that Beyer says weren't horribly old but nonetheless were unwanted. Using essentially free monitors, keyboards and mice, Beyer and Szaky built their network. Using open source, they developed their applications: The most recent iteration of the ERP-related software they developed in-house uses Ruby on Rails, says Beyer.

"The decision to use open source was based partly on the fact that it's cheaper because it's free. But we also thought it was the best platform to develop on," he says. The hard drives on the used equipment came wiped, and Beyer says he didn't run into any problems as he got the systems up and running. "We probably have a slightly higher hard drive failure rate, given that most of them are five years old," says Beyer.

As TerraCycle expands, Beyer says he will continue to buy used and refurbished equipment. In fact, the company owns only one new piece of equipment: a copier.