We built in Kildare ourselves over the past year, and costs we incurred from a planning perspective were:
Architect fees for drawing up the plans (approx EUR 3,000)
Fee to submit planning application & post notice in paper (EUR 65 i think plus newspaper advertisement maybe EUR 50)
County Council development fees (vary by county, and charged based on size of house, ours were almost EUR 15K for 2,600 sq ft but fairly sure they would be considerably less in Co. Roscommon)