@Allen Zhu -Reading, along with many other eastern Pennsylvania markets are seeing significant growth compared to other areas in the state/ country.

Generally I'm seeing anywhere from $25 - $40/Sf in TIA in different markets around the country. 

I'd build up and go for at least 2 units but 3 stories is better. 3 story walk up apartments account for almost 65% of apartment developments round he country. this is what I'd recommend on your lot. this is 35' tall and we do it in columbus oh 

I doubt you will have to do this, but some areas of the country are nutsy...

There are also some unique medium term rental strategies that can be implemented in bigger cities throughout the country.

Yes BofA is all over the country but if you go to your local branch it's pretty likely that loan officer and/or office wouldn't be licensed to operate in another state. 

That is just what I am seeing personally, and I work with investors all over the country. 

Start with a country subdivision versus a city one.  

Purchase price: $675,000 Cash invested: $250,000 Country estate with 2 houses.

I work with several real estate developers across the country and they all do it differently.My suggestion is to find a property type and an area/neighborhood/city/market that you are drawn to and plot your course from there.As for the amount of money you'll need, it's gonna be mostly driven off the purchase price of the property.