Nobody pays for votes with money. Not directly at least.
People are paid in deals, jobs, favors - which they get to enjoy AFTER they elect candidate X.
Supply contracts, appointments, sponsorships, various consulting positions... once elected X gets handed a whole ball of strings that can be pulled for people who've been good to X.
Your boss doesn't have to order you to vote for candidate X. Nor does candidate X have to bribe you to get your vote.
Your boss just needs to mention that he/she hopes candidate X will win cause that will mean a secure government contract for the company.
They are friends from back in your boss's goat fucking days, and you know how goat fuckers "stay tight".
And for a "small-ish municipality (between 10,000 to 15,000 in population)" one would probably only need to acquire a couple of hundred votes, one way or the other.
10000-15000 is about 7500-11250 eligible voters.
At about 60% turnout, that makes 4500-6750 votes, total.
At very worst, with a single opponent, you'd need 2250-3375 votes + 1 (or whatever is the necessary majority).
I.e. Not even a quarter of the population.
Now... how many of those people or their spouses and family (Remember, married people count as two votes each.) are already on the municipality payroll, one way or the other?
Police, fire department, utilities...
Those are the votes you buy directly from the budget.
You only need a couple of percent of "real" voters out of those 2250-3375.
I.e. People with influence over other voters.
And yes... The incumbent official has it much easier.