She cant do a short sale because she can afford the house. 

In comparison to other Boston areas, it is considerably more affordable, especially for investment properties.

Could you afford that? 

The most "classic" and affordable are single family homes but some investors prefer the "2-for-1" duplex option for first time investing.If (1) You're able to move, and (2) you want to be creative with your financing, I purchased a duplex (my first investment property) and did 5% down FHA loan.

Therefore- it is used to help them afford a house purchase.

I suggest you determine what the value of the opportunity is before determining Jim much you can afford to budget finding the owner.I use the following acronym: PETIOPROPERTYEQUITYTITLEINTERESTSOPPORTUNITYWith this format I can determine where the sweet spot is in the situation.Since you are hopefully chasing a bunch of equity, you might be able to budget $50-100 or even more to skip trace a missing owner, if alive. 

I use the zillow mortgages app to see my affordability.

I can not afford anything in NYC unfortunately.

I'm really excited to join BP as I'm just starting to learn more about real estate investing.A little bit about me:I'm currently working on finding ways to help provide affordable shared housing in the Bay Area.

Even after moving out the cash flow should be positive enough from both units so that you can afford to handle all the long term maintenance and tax increases and still make a profit.Betting on appreciation is risky as far as I am concerned.