If you don't know your repair costs yet, which it sounds like you don't, then figure out all the other pieces of the puzzle like the ARV (after repair value) by looking at comps, figure out your financing costs by talking to lenders, and you can back into what your maximum repairs could be.

LABOR is the most expensive piece of the puzzle.

Good luck sorting this puzzle out!

I was puzzled about the different FSBO financing options and how would they affect the profits within different amortizations/ down payment/ interest rates etc. 

If you could help clarify my puzzles on the topic, it’s will be greatly appreciated.

Lots of pieces in the puzzle. 

it was a puzzle how to support the walls and slide the full sheets of plywood in.

The land is the cheap piece of the puzzle for 2-4 unit construction.If you want to build for yourself, you need to find a builder that you can work with and is able to do the project. 

You have to work all pieces of the puzzle at the same time when you start out, and you will never have the complete picture of any one piece until you pull the trigger.Like @Cassi Justiz said, most HML can ballpark rates, but they may have lending tiers, so they cant finalize numbers until they see the numbers for a specific property.

It’s been puzzling me for a while.