Once I have a family, the comfort level will prob be around 150k to 200k.
Also, 300sq ft. is not enough. I had a maybe 500 sq. ft. place in DC I was living in for a while. It was OK as a temporary solution, but I could practically extend my arms and touch both walls.
I think about 800sq ft. would be an acceptable minimum. Preferred minimum would be about 1000sq ft.