Houses are cheap mostly because they are in places no one wants to live anymore, normally it is small towns in the middle of nowhere, they may have some appeal if you like this type of things, but in general the towns have a strong decreasing population, and they are difficult to reach. Above all locals don't really like foreigners, they normally don't speak English and they may even think you are exploiting their beautiful village (everyone in Italy thinks his own village is the most beautiful in the world)
Renting and reselling prices will be an issue, there is not much money in those areas.
There may be opportunity in less cheap areas, big cities or touristic costal areas still undeveloped. But there the issue is dealing with local authorities, that again are not friendly to any entrepreneurial initiative. Recently in some costal areas some new touristic resorts have been built, this is maybe something to look at..