How much a 80sqm apartment costs depends on the location on the coast and how close to the sea. Anything from €1000 per sq. metre and €3000 or more. Prices are higher still for waterfront properties (which are also in short supply). The condition of the property is less of a factor - basically unless you are buying a new build, you can expect to do some renovation work.
BTW 80 sqm is considered a large property in a country where whole families can live in 60 sqm. Evem 45 sqm properties are common.
Hello,
I have bought an apt in Korcula, the property overlooks the sea and swimming pool, and is rented to holidaymakers in our absence, we bought over 5 years ago, but I have seen them advertized for around E140,000. Good luck with your search, we love Croatia and have never regretted buying there.