And the answer is always the same :-) There is no way to accurately do this...too many variables and moving parts, plus it varies too much from one locale to another.You need to find a really good General Contractor and pay him to walk the property with you....over and over....until you feel really comfortable estimating yourself, and that should take years.Alternatively there are online calculators (even one here in the tools section) but I would not rely on them for the reasons listed above.

lets say ive saved up, got preapproved, do i then get buyers agents to look for homes for me? 

With this mortgage, that would save me $22,500.

We've managed to save about 30% in a relatively short time for our dream home in her home town, worth less than 200k USD.

I have 20k saved and plan to use an FHA 203K loan and house hack to net zero/cash flow minimally on my first investment.

I bet your systems are amazing, and you probably save a bunch in economies of scale. 

Just depends on line of site and distance to connecting road if they will allow.

On the West End of Shrewsbury street by Union Station you have Alta on the Row which will come on line in the next 6 months, from here you can walk to Saint Vincent's hospital very easily along with MCPHS. 

I have 90k in cash in a savings account. 

My first investment was a condo, and I wish that I would have either waited to save up more or taken on a project to buy a single family home.