I don’t think $300 sq foot is happening in 2021, not all in costs at least.
I actually got a quote from a coastal small complex developer circa 2016. It was $500 sq foot.
Saying it doesn’t have to be “high end” doesn’t actually save you much. Nice fixtures barely add to the cost, which is why mid-range apartment complexes intended to rent for under $1000 a month in the midwest still have granite countertops.
