Yes, there are very strict limits on how much a candidate can spend on election campaigns. These limits exist to ensure a level-playing field between the different political parties contesting the elections.
 
The amount that can be spent depends on the number of registered voters in each electoral division. The current limit is S$4.00 per registered voter.
 
In a Group Representation Constituency (GRC), the amount is calculated by dividing the total number of registered voters with the number of candidates in the GRC.
 
Election expenses, which are any expenses that goes towards the management of the candidates’ election campaigns, are open to inspection. The Returning Officer requires a declaration and returns on election expenses. This must be submitted within 31 days after the elections results have been published on the Government Gazette.
 
It is illegal for a candidate to spend beyond the imposed limit.
 
Source: Section 9 of the Handbook for Parliamentary Election Candidates