It would be nice if they split the difference. Basically a Small House would be 150k, Medium House 300k, and Large 450k. That would make the math easier, though that would be a lot of gil considering there is virtually no way to make gil (NEW gil) so not sure how that would work for upkeep costs. Hopefully it is not something like 10% of total cost per week/month (though /month would be easier to handle I suppose).