Dividing medians by medians is not safe; you get weird interactions between differences by region and differences within each region. (Houses in Manhattan are smaller than houses in Cheyenne, and also cost more, because the cost per square foot is higher; but in both Cheyenne and Manhattan, bigger houses cost more. Except when you get into the ghetto/non-ghetto distinction, etc.)
Also I don't think the medians you cite are anywhere close to correct. Maybe they're correct as medians only within the US? I remind you that the US is less than 5% of the population.
Otherwise your figures look good to me.
Maybe the right answer here is to pay attention to your current region. I'm paying about US$350 per month (before taxes) for 60m², about 600ft². For me 40 books per square foot means each book costs about ⅝¢ per month to store. I think that's about US$0.68.
Also I don't think the medians you cite are anywhere close to correct. Maybe they're correct as medians only within the US? I remind you that the US is less than 5% of the population.
Otherwise your figures look good to me.
Maybe the right answer here is to pay attention to your current region. I'm paying about US$350 per month (before taxes) for 60m², about 600ft². For me 40 books per square foot means each book costs about ⅝¢ per month to store. I think that's about US$0.68.