if it were me buying the house under construction (which it wouldn’t be) I would spring for the $15K to add the balcony
1. $15K is insignificant relative to the overall cost of the house
2. it will cost me a lot more than $15K to add a balcony later if I decide I want one
3. there might be some hot co-eds in the house behind me that I can watch from the balcony (just kidding)
there is something attractive (romantic?) about standing on a balcony and over-looking your estate – I wonder how long this feeling lasts when the ‘estate’ is a few hundred SQFT of grass surrounded by fences and neighbors