We lived in the 2 bedroom side of the property for a year, keeping the current tenants on the 3/2.In June, 2017 we increased rent from $800 to $850. 6 months after that, we purchased a home to live in (with our 2nd child just 3 months old) and moved out, intending to renovate the 2/2 we'd been living in.In August 2017, after moving, we started renovations, which (of course) took longer than expected and cost more than estimated.

Check out the sold comps in each area to give you a ballpark estimate.  

Then figure out an estimate of what the MIL suite would use and add that into the rent.Example: Average cost of all utilities is $250 a month.

I have the price listed well below the estimates, and it's price per sq ft is well below average.

I have the price listed well below the estimates, and it's price per sq ft is well below average.

So those may last another 3, 5, 7+ years (if you haven't recently replaced them), but you will want to budget for them in your calculations.You could potentially account for less in your budget for vacancy, repairs, and cap ex, and you might be able to show an estimated positive cash flow, but in my short time on this site, I think most would suggest that in your budgeting, you should budget more for those expenses, rather than less just to try to make a deal "work."

Even if you have everything in writing, you still will miss few things.Also estimates for work are just estimates.

One thing I have noticed is that in some markets the offered price for Turnkey investment seems to be much higher than market estimates from Zillow or other sites.

Check this out too. https://www.biggerpockets.com/house-flip-estimation-calculator

Plan on 25% for an investment property.Your Expense estimates look good and conservative.