When Martin Shkreli, the former CEO of Turing Pharmaceuticals, hiked up the price of a life-saving medication, one group of high school students saw an opportunity to do good.

Eight teenagers from Sydney Grammar School in Australia have collaborated with scientists from the University of Sydney to reproduce the active ingredient in Daraprim, a drug whose price tag swelled from $13.50 to $750 last year.

How much did it cost them? A mere $20.

Working in their chemistry lab, the students synthesized 3.7 grams of pyrimethamine, the active ingredient in Daraprim. That yield is worth about $110,000 in the U.S., according to the BBC.

Daraprim is an anti-parasitic medication used to treat malaria and other conditions involving compromised immune systems, such as AIDS. It is listed on the World Health Organization’s list of essential medicines.

University of Sydney The students from Sydney Grammar School.

The boys, all 17, called their project “Breaking Good.” Under the guidance of Dr. Alice Williamson and Associate Professor Matthew Todd, they worked with the Open Source Malaria consortium, which allowed scientists anywhere in the world to view their data and offer feedback.

“This Daraprim story has been ingrained in lots of people’s minds,” Dr. Williamson told CNN. “I thought ‘what if we can get these boys to show you can make it from cheap materials and that relatively inexperienced young scientists can make it?’”

“We knew it was a good story and the boys have done a good job,” she went on. “It’s really captured people’s imaginations. They made a very pure sample of the active ingredient.”

University of Sydney Students in Australia used inexpensive starting materials (left) to make a sample of pyrimethamine (right).

Turing Pharmaceuticals acquired the exclusive marketing rights to Daraprim in 2015 and quickly moved to raise the cost. Shkreli claimed that the decision was a strategy to make money from insurance companies and that the funds would be used to research better treatments.

The patents for Daraprim have expired, but Turing still has exclusive rights to sell the drug, meaning the boys from Sydney can’t simply open up a shop in the U.S. and sell their own, affordable version.

Shkreli ― who, whatever else you can say about him, isn’t afraid of bad P.R. ― belittled the students’ accomplishment on Twitter this week.

@nedavanovac lol how is that showing anyone up? almost any drug can be made at small scale for a low price. glad it makes u feel good tho. — Martin Shkreli (@MartinShkreli) December 1, 2016

@Scottyt2Hottie yea uh anyone can make any drug it is pretty ez — Martin Shkreli (@MartinShkreli) December 1, 2016