Candidates who can't find 30 nominees must pay a deposit. But if they can't find 30 nominees, they are probably not going to get enough votes to get their deposit back.
From Wikipedia
In the
Republic of Ireland, candidates for election to
Dáil Éireann who have been nominated by political parties registered to contest Dáil elections, as well as non-party candidates who are able to provide detailed information of 30 electors in the constituency who have assented to their nomination, are not required to pay a deposit. Candidates who fail to meet either of these criteria, however, must pay a deposit of €500.
[10] This follows a
High Court ruling; the court found that the obligatory payment of deposits by all candidates was repugnant to the
Constitution of Ireland.
[11]
Candidates who paid the deposit are returned if their final vote total, under the
single transferable vote electoral system, exceeds one-quarter of the
Droop quota for their constituency; i.e. in a four-seat constituency, the quota is 20% therefore the deposit threshold is 5%. This is also the threshold that candidates' votes must exceed in order for them to claim an election expenses allowance from the State.