A superintendent in Guangzhou has earned enough to buy an RMB140,000 car and a 70 square metre house by offering private sperm donation services over the past 18 months, Want China Times reports.

Duan Kuan, who is married, completed his first injection in February 2012, charging RMB500. He has since raised the price of his injections to RMB1,000 a go.

Duan studied how to augment the fertilization rate, such as helping customers select the right timing and device for introducing the sperm into the body.

He apparently meets his clients on social networking sites. Want China Times has more:

They might meet a bar or other public venue, where Duan slips off quietly to the bathroom and comes back with a sample in a box, on ice. He has even donated directly into a female client, with consent.

While some online sperm donors offer free sperm, mostly with illicit intent, Duan said that his paid services give clients the assurance that he is conducting a business.

According to Xinkuaibao, receiving a sperm donation through official channels can cost thousands of RMB, so Duan’s business may have a future.