STR looks like an attractive option but I am a novice in this area so looking for input on realistic income and cost estimates of a STR managed by a 3rd party property management company. 

This property is primed for short term rental (night to night) with conservative estimates of ($40,000-$50,000) per month.

A lender should be able to get you a estimate on monthly payment so you can plan ahead

I'm estimating at most I'll cash flow about $250/month once complete. 

@Brad Tracy The most recent estimate I got to renovate an existing space to a studio apartment was $120K.

We have equipped our 3 GCs on payroll to understand this program and can now help others get access to the information and provide free estimates for work like this in all over MA.

Failed listings could mean canceled listings, expired listings, or where there have been no updates to a listing for X period of time and they just move them to failed.Equity could be calculated based on FMV - original mortgage OR FMV - estimated current mortgage amount. 

Real Estate is definitely not just a "numbers analysis" and you are definitely thinking about things the right way - but I think a good next step for you would be to spend some time putting a lot of this stuff into a (very) basic financial model/spreadsheets mapping out all the potential costs and estimates on effect (effect on value, on exit, different scenarios) - I think getting started with that framework should help with these decisions immensely

Estimated rehab about 44k but may be less ( I wanted to be conservative). 12.99% annual interest rate, Originator fee, 2.99 points, closing fees $990.

However they haven't had any other offers and it has been on the market for roughly 70 days.At the accepted offer rate our mortgage would estimated be:Year 1 - $5231Year 2 - $5750Year 3-30 - $6292Each of the 3 units would rent for an estimated 2-2.5k totaling roughly 6k-7500 per month in income depending on what we can rent each unit for.So with all that being said, conservative numbers the triplex would cashflow roughly 1k per month assuming we don't live in it and have all 3 Units rented.That seems like razor thin margins, especially when factoring in expenses so my question is:What is the cash on cash net return per month you would look for in a triplex deal like this?