I would like to legalize it and was wondering if anyone would be able to give me a rough estimate of the cost to convert the property to a 3 family.It does not have a sprinkler system. 

PP 350k, Estimated rent 3k, looking at PITI of $2150/month.

I am currently doing a construction estimating internship in Milwaukee Wi.

I'm now courting builders for plans and estimates, narrowing down to few I've shortlisted. 

The MAO formula (70% of ARV Minus Repairs Minus Wholesale_Fee) only makes sense for fix-and-flip deals.For rental deals, you'll need to calculate the metrics that matter to a landlord, starting with Cash Flow and Cash-on-Cash-return.To do this you'll need to estimate Income and Operating Expenses to get Net Operating Income (NOI).

Second lowest property taxes in the nation behind Hawaii.Montgomery county tax estimate formula is: appraised value x 20% (without homestead) x .0365

Scott The Book on Flipping Houses,The Book on Estimating ReHab Costshttp://www.biggerpockets.com/flippingbookLocate and attend 3 different local REIA club meetings great place to meet people gather resources and info.

My estimates are that I would NET $100k per property after taxes and commissions.My income will basically stay the same. 

Unless you have a specific property under contract, there really isn't anything other than some rough numbers and estimates. 

When looking this property up on Zillow (one of the recommended steps in the book) I see they estimate the value of the property as $28,965.