It depends - the general cost is around 10K EU a hectare - some have ruins, which I think are fine to build on, others are in agricultural regions saying 'no building' but if the later it's easy enough to live in a van or Yurt pretty much for ever as several people do around here.

I'm going to have to get out and have a good explore.

I know a couple of people with some land for sale very close by - 26K for 3 HA on a mountain side, that has a ruin and you can build, it's just a bit more than I want to spend, it'd wipe me out, and I need money for other development things.

I'm tempted to go super cheap - 10K for some degraded agricultural land.

We'll see!