Someone writing $200.00 on a cocktail napkin does not guarantee an audience with the seller, if the seller does not want it.

I just don't want to get caught with having to ask the seller to provide the appropriate forms or, worse yet, a cocktail napkin contract.

I got some clarification from the realtor.He says:Option 1 best case scenario new concrete septic take in same location $3500-$5kOption 2 (likely if tank has not been updated) new septic tank and drain field $12-$14kOption 3 (generally not required in this area but possible) New "ATT" system and tank, field $20-$25kHe is meeting the county sanitary guy on Monday to review information they have on file. 

It's better in my opinion to have price estimates on individual upgrades, i.e. the cost of a roof, cost to renovate a bathroom, cost for a new boiler, etc.Obviously these are just back-of-napkin estimates, so I'm open to hearing other opinions as well. 

Sorry I don't use those things.. its all in my head and on a napkin.. the math is simply too basic for me to delve into it any deeper than that.. plus its all supposition.. so I don't get caught up in trying to model things out that I cant control.. other than the very basics.so my spreadsheet in my head is simply  50% of rents are costs of some sort over the life of the deal.. and I think this is a good market and I think in 10 years the house will go up this amount..   

As for your first question, "what would you be looking for", here's some back of the napkin math: $1900/mo in revenue equals $22,800 annually.

Maybe someone who knows the Avondale area can comment more if this is accurate.For taxes, my estimate was $6,976.31Back of the napkin math:2020 Projected Assessed Value = Purchase Price * 10% = 38,007 2020 Estimated Equalized Assessed Value (EAV) = 2.9160 (2019 State Equalization Factor) x 38,007 = $110,828 2019 Total Tax Before Exemptions = $110,828 x 6.919 % (2019 Local Tax Rate) = $7668.21 Homeowner's Exemption - 691.90 2020 Estimated Tax After Exemptions = $6,976.31Note: I am not a tax professional, just sharing how I estimate taxes.

But I was curious - just based on the listing, and the homework you can do vis a vis comps and the neighborhood...... what would be your back of napkin guess for rehab cost, and ARV? 

Here is my back of napkin for this deal: $520k purchase

Depends on the city and Government regulations, and how many lots, you may have to invest in common utilities/facilities (roads, parking, water, sanitary sewer, fire water requirements, storm sewer, to mention few), making the cost per sqft higher, and that's a chunk of $$.