For example, they'd agree to do something for me for a fee of, say $1000, then I'd get an invoice for $2000 b/c it exceeded their estimate. 

Market value estimation is never a specific percentage range above or below list price, I realize a lot of 'methods' teach this, but that is starting from the wrong end of things.The question is, what is the market value (regardless of list price, which the listing agent seller could have set at high, low, or spot on)? 

This deal is located in NW Indiana numbers are roughly estimated, I am planning to buy my first rental property with FHA loan, live there for one year, then move out and rent it out, Screen shot and Link to the file are attached below.

We have the figures for total cost to build, cost of loans for new construction and the estimated time frame to complete it before we would have renters. 

The Chinese Land Reform Movement lasted from 1949-1953, during which time the communist leader Mao Zedong rounded up and murdered an estimated 2-3 MILLION landlords, he then redistributed their property to the peasantry.https://en.m.wikipedia.org/wik...

Used cash flow analysis and repair estimate worksheet to justify price.

This deal is located in NW Indiana numbers are roughly estimated, I am planning to buy my first rental property with FHA loan, live there for one year, then move out and rent it out, Screen shot and Link to the file are attached below.

Latest rate and term refi recorded was 2012 at 200k which has been estimated to be reconveyed but who knows.

You bought an unzoned illegal duplex at $90K that you're going to need $100K to fix (and I assume this renovation estimate comes from the guys that sold you the place).

This deal is located in NW Indiana numbers are roughly estimated, I am planning to buy my first rental property with FHA loan, live there for one year, then move out and rent it out, Screen shot and Link to the file are attached below.