I live in Zagreb and it is a great city but..
- property is not cheap, even relative to Ireland
- rental return is quite low
- limited new development in the city, mostly office recenty
- much of the available properties require complete renovation, air con etc
From properties that I have seen for sale, You could pay between 70,000 -450,000 for a two bed apartment depending on distance from city, area etc
From the people I know here who rent ( I am in serviced accommodation so not a fair reflection) they are paying between 250 a month for a one bed to 420 a month for a two bed in the city centre.
The one thing that does seem interesting in Croatia is coastal property. The rental season is getting longer and the capital growth is good at the moment.
If you have any specific questions, I can adopt my ask a local strategy !