Of course, you can never wait until you have everything, but it seems like there is significantly less one has to work with before starting real estate investing, making one's attempt feel more like a gamble than a calculated risk....Or is there?

I would like to include this expense in my flip calculator as accurately as possible so as to not underestimate this potential problem.

The danger of posting in a public forum is that you will get lots of opinions but not always informed, accurate and useful responses.I agree with @Jay Hinrichs.The primary issue at hand is that you need a seller who has capacity, power and authority to pass marketable title to you. 

The other is gamble on the open market and maybe get $85k. 

Gamble / Play the lottery3.  

So add points on top and you should be pretty accurate.

@Ndy Onyido   Nothing is certain, everything is a gamble.   

But its a gamble.

However, for accurate, useful information, walk the house with your contractor, foundation person, HVAC person, etc.  

If 35% of what you read is accurate, it's a lot.