There were weeks I worked 60 hours but it was generally doable for me to arrive late and or leave early, I just needed to be available on short notice.

Rent check then arrived within the week after the tenant was notified of this. 

Scott and available for purchase on this website. 2. then watch the webinairs or read what's written by Brandon Turner - he'll explain how you absolutely need to know the ARV, the rehab estimate, and the minimum amount of profit that you want to make on a rehab - before you even consider making an offer - because THAT is the only way you can arrive at the offer price.And you need to hit the streets (the open houses would probably be OK too.

If you want to do a rough ballpark to see if you might meet this, pull up your most recent tax returns (or 2017 before you file them), look at net taxable number at the bottom of Schedule E, add back depreciation and mortgage interest, divide by 12, and subtract your P&I payment (we removed just the interest earlier, now we're including the P&I) to arrive at ballpark monthly true net cashflow, and compare to personal monthly debt obligations.In your case, the strategy might be to find a local lender that'll entertain this, take out as much as you can using Fannie money, and only use hard money once you're tapped out of Fannie money. 

That is not how expenses on a income property are arrived at in the real world.

Any suggestions how to arrive at this ballpark figure?

The notice arrives in my inbox; I login and accept, and all is right with the world.

Assuming you are able to eventually sell for 105k, then subtract ALL the costs of rehab, holding, financing, paying realtors, back taxes, etc... and your desired profit, you'll arrive at your maximum offer price.

.- Have info on file about how you arrived at the amount of the fee.

I'm not trying to convince you one way or the other, but rather implore you to arrive at your decision on your own, based on your extensive research and reflecting on your situation.