Ratepayers have put $70,000 toward an American conference in Christchurch this year, which charges up to $3495 for tickets.
SingularityU is a Silicone Valley corporation which looks into fast-growing technologies and how they are likely to change the economy, society and the job market.
The three-day summit in November is the first to be held in Australasia, and is organised by Ministry of Awesome co-founder Kaila Colbin.
The city council approved the grant, which is from its Capital Endowment Fund, behind closed doors.
The funds will help to provide scholarship tickets to Cantabrians who apply for them.
Deputy Mayor Vicki Buck said the city council often supported events which brought people to Christchurch and added value to the city, and she believed it was a good use of money.
But former city councillor Aaron Keown said the public hadn't been allowed to judge if it was good use of money, because it was decided behind closed doors.
"If the council is going to spend ratepayer money on these conferences, they need to be open and transparent and stick to the process."
Cr Buck worked with Ms Colbin to start the Ministry of Awesome, but she said there was no conflict of interest there.
"She happens to be one of those people who do an amazing amount for the city, and I happen to know quite a lot of those people," she said.
SingularityU was a non-profit organisation until 2013, but now functions as a business.
But Ms Colbin said the summit was not there to make money.
"I have worked for free for over a year to get this off the ground, and my current salary is under the median salary in Christchurch. So no one is doing this to get rich."
She said her goal was to share information she believed was vital with small business owners and entrepreneurs in Christchurch who could not afford to go to conferences overseas.
Full-price tickets to the summit cost $3495, but about half the 1500 tickets will be set aside at $995 for educators or non-profit or start up staff, and $245 for people under 25.
She said 10 times the amount the city council put into the summit would be spent in the community through things like the venue hire at Horncastle Arena.
Both Christchurch International Airport Ltd and the Canterbury Development Corporation are silver sponsors of the event.
CDC has put $15,000 into the summit and is helping to raise awareness of the event, a spokeswoman said.
The airport company would not say what its contribution was.
Airport aeronautical chief commercial officer Justin Watson said he had attended the SingularityU executive course, and he believed it was important local people were engaged in the discussion.
"We believe exponential technologies will profoundly impact every one of us, both personally and professionally, over the next few decades."