Very rough analysis:Gross Rent Amount / 2 = Monthly Cash Flow Assuming No MortgageIf there's a mortgage, subtract the monthly payment (P&I) from the result above to get the monthly cash flow.If that analysis works out well, the deal is good enough to pass  to the buyer to let him plug in his own numbers and come to his own conclusion.

Depreciation is not an 'expense' per se, but its treated the same way ie. subtracts from your taxable rental income, same as taxes or mortgage interest.

After subtracting all my normal monthly living expenses I only have an extra $10,000 each month that I can put into this going forward.

Anything I should add or subtract?  

(Subtract that from sales price to get loan balance.) • How much are the monthly payment on the mortgage?

That is taking the "As is" Annual Revenue of $90,780 and subtracting what the owner has as the following expenses; Gross Income: $90,780 Vacancy (5%) (4,539)Electricity (14,400)Water (6,000)Trash (1,500)Gas (3,000)Lawn (900)Maintenance (2,400)Insurance Expense (6,000)Property Tax (5,962)Advertising Expense (600) Net Operating Income: 45,301These are all current expenses not Pro Forma.

Some investors like  @J Scott prefer to work with actual numbers for those costs then subtract what he wants as a profit margin to figure his offer. 

So I subtract cost to build from comps, giving us 250k.  

Let's look at some rough numbers: Income 1100/monthMortgage 900/mGross 200/mNow let's take $200/m and subtract expenses....8% vacancy $88/m5% reserves $55/m10% management $110/m5% repairs $55/mAlready your at a monthly cash flow of -$108 and I left out more expenses because I don't know the specifics of the deal.

Which one of these scenarios is the typical scenario for a wholesale fee:Scenario 1: ARV * .7 - Repair Costs - Wholesale fee = Total Offered Price (Subtracting wholesale fee for total offered price)ORScenario 2: ARV * .7 - Repair Costs = Total Offered Price (Subtracting wholesale fee from ARV, or in essence, receiving your wholesale fee from the investor for what he/she sells the home for.)Sorry if I confused anyone. :)