The two candidates who contested the Bukit Batok by-election spent a total of $169,291 on election expenses, with Singapore Democratic Party chief Chee Soon Juan spending more than Mr Murali Pillai of the People's Action Party.
Dr Chee spent $3.39 per voter, while Mr Murali, who won the polls, spent $3.19 per voter.
In all, Dr Chee's expenses reached $87,200.
His biggest expenditure - at least $38,280, or almost 45 per cent - went to printing and distributing traditional campaign materials such as posters and newsletters, according to receipts submitted to the Elections Department, which made them available for public inspection for six months, starting yesterday.
Another big-ticket item was the holding of four rallies: They cost at least $33,673.
These two items made up about 85 per cent of his total expenditure.
Mr Murali's bills came up to $82,091.
Like Dr Chee, his rally logistics and campaign materials formed a huge part of his total cost.
The two rallies he held cost $28,590, while his expenses on traditional campaign materials added up to $27,331.
The May 7 by-election, triggered by the resignation of MP David Ong in March, was won by Mr Murali with 61.23 per cent of the votes against Dr Chee's 38.77 per cent.
During the campaign, Mr Murali hired local production company Freeflow Productions to film and edit three videos, including one that had him speaking in Mandarin and asking residents to call him "Ah Mu". This cost him $9,630.
The SDP spent $3,852 on postage for 10,793 letters. It also paid engineering company Multi Wall Engineering $14,659 to distribute 28,000 fliers and deliver equipment to rally sites.
In contrast, social media expenses were much lower.
Dr Chee, who had said at last year's general election that social media helped change people's perception of him, spent $646 on Facebook advertising against Mr Murali's $317.
Dr Chee also dished out more than half of what Mr Murali spent on food for his activists and volunteers: $5,369 versus $2,356.
Dr Chee's bill, however, included a $2,354 thank-you dinner for 100 volunteers after the by-election.
A PAP spokesman said Mr Murali had a volunteer who cooked many of the meals.
A three-page-long grocery bill amounting to $454 showed such items as 50kg of rice and six cans of luncheon meat. In between, receipts showed that his volunteers enjoyed McDonald's nuggets and Old Chang Kee curry puffs.
Both candidates' bills for the by- election were within the $102,908 legal limit, or $4 for each of the 25,727 registered Bukit Batok voters.
The law requires candidates to submit their election expenses to the Elections Department after the polls.
Besides election expenses, the candidates also had to declare the donations they received.
Mr Murali said he received $82,091 from the PAP headquarters, a sum that covered all his election expenses. Dr Chee said he did not receive any donation.