this is just new to me), so I'm using very basic a very basic formula for each non-static item as "averages".

The only hope you have is to give away the store, which, of course, leaves you broke.It's a nice ego rub to have your own brokerage, but ego doesn't pay the bills.

otherwise let me be the first to say, RUN. do not buy this. ok with that out of the way, a few things you can adjust to give you a more realistic picture in the calculator. no matter what you'll always be spending some money on repairs when you first get into a place, so off the bat i would put a grand or two for estimated repairs. i run my vacancy numbers at 8% as this is just about a month. your capex should be lower, unless this place has some really big ticket items waiting to die. same with repairs. also the insurance numbers and property tax number both seem very high, is this the real numbers or just place holders?

ARV = (Property’s Purchase Price) + (Value of Renovations)You can most accurately calculate this when you understand how how much value each rehab item will bring THE BOOK ON ESTIMATING REHAB COSTS by Bigger Pockets will help with figuring that out or you can checkout an article they already published going pretty in depth on the topic for quickly analyzing ARV's when searching for a deal.

If you find an issue during visit, home inspection, any other due diligence item that adversely affects the price then lower the offer or walk away.Good luck

I purchased 2 of the windows I needed at the builders outlet store, and they luckily had sizes that fit.

The few items I see that you (maybe) missed were capital expenditures (CapEx), Lawn/Snow care expenses, and $1,500 for maintenance might be kind of lite if the property is older/not updated.  

Maybe you wouldn't immediately remedy cosmetic items that they would require you to fix or face fines).

How about an itemized list of What they fixed or repaired or replaced. 

You can sell what you already own if you do not need those items or can easily replace them.