Platinum Enterprise spokesman Pierre Wong said the group chose the issue because one of its members' relatives was affected by the condition.
There was a lot of media attention on breast cancer but not a lot on the subject of prostate cancer, he said.
"Our group couldn't even find the logo for it. We didn't know what it looked like."
After finding the Prostate Cancer Foundation logo on the internet, the group decided to promote the issue on singlets.
The price of the singlets was set at $25, which the group believed made them affordable while covering all its production costs and allowing for a 30% donation to the foundation, Mr Wong said.
Platinum Enterprise met the Minister of Finance and Clutha-Southland MP, Bill English, on July 8 when he was visiting Balclutha.
Mr Wong said Mr English had questioned them about the young enterprise scheme and what the group had learnt.
"Team work and communications skills," Mr Wong said.
He added that although Platinum Enterprise would like to make some profit, the main object was to increase awareness of prostate cancer and men's health as much as possible.