>The thing I found most remarkable is that house prices there are not much less than in Seoul proper (that's what I was told at least), which just seemed utterly absurd - what market forces could drive prices of a farmer village (because that's what it is, really - although the houses looked nice) surrounded by landmines and that is a pain in the ass to get in and out of to that of a first world metropolis?

You are literally paid to live there and be a human flagpole through a tax-free salary of $82,000 USD for agriculture (as of 2013, likely higher now), as well as free education, agricultural incentives and preferential tax treatment. [1] On top of that, there's only a handful of homes, effectively amounting to an artificial housing scarcity.

[1] https://modernfarmer.com/2013/11/guarded-growing-farm-centri...