Since I am fairly sure this would be on Legends it would be a less populated shard. Napa Valley is similarly small, and I sold an ice Tram castle here for about 150mil value in trades and checks.
I doubt a Fel castle would go for less, because everyone left in Fel naturally wants to upgrade to the 'end game' building unless they have Grandfathered homes like me.
My experience was that most people 'are holding out for a 60mil castle' on these shards. But then, when someone is actually looking to buy one, one might do even better than I. It really just depends who is in the market at the given moment.