Rehab costs that are under estimated by very wide margins.  

There are a few items I have no idea about, I'm hoping someone here has some experience in the field and can provide a ball park means of estimate 3 costs:1.

What I really look for in a agent is can they confirm or deny my ARV and rent estimate and explain why.

I'm just north of the lake, thinking of doing the same, have about the same equity, and my estimates ($3500/mo) seem to cashflow a couple hundred a month.

I got several estimates from roofers and the replacement cost is around 13k (it's a ~1600 sqft house).

They provide free estimates and work with your accountant.

Times change, markets change, interest rates change, but we still hear about these same old "rules" decades after they lost their relevance.The same logic applies for napkin math rules that say that capex, vacancy, repairs, or whatever, should each be estimated at X% of monthly rent. 

I had an estimate done ($7k) because at this point the sprinkler piping is exposed and I'm afraid that could lead to an even greater problem.

There are an estimated 1 - 2 million crimes a year stopped by brandishing a gun and fewer than 600 deaths from accidental shootings.Pepper spray is not as effective.

The BP rental estimator tool is pretty good as well and is usually within about a 5-7% margin of error.