The goal is highest rent for lowest investment cost and lowest maintenance.

You might win, but it may cost you money to win and hire a lawyer to defend lawsuits. 

What did it cost?

Once you begin to generate leads that fit their recent purchases/want to buy, run the numbers based on the ARV after repair value for after when they develop/fix n flip and subtract cost of build/repair, your assignment fee, and the original cost of the contract.

If you roll into town and you see a Marriot or a Motel 6, it's pretty obvious to you which one will (probably) cost more and which one will (probably) be a lot nicer.

I estimate the cost to be about $200,000 based on no hard data but the DSLD house that I bought cost $270,000. 

It is a nice amenity that doesn't cost much.  

Here's a breakdown:Project Details:Property Cost: $50KRenovation Costs: $30KResale Price: $100KProfit: $20K ($100K – $50K – $30K)For instance, if your regular income is $50K, and you add the $20K from the house flipping, your total income becomes $70K.

I added a 5% charge to vrbo to offset the extra cost  

My question is, are there any other potential causes for this sewage backup, and anything else I should be thinking about that could make it much more costly than $1,000 or so to remediate?