Buying and converting an Arlington, VA single family to duplex?

[Account Closed]

We are looking to buy what will be our primary home in the next year and are considering purchasing a home (townhouse or detached) and converting the basement into a legal apartment to rent out to help offset some off the mortgage.  Because duplexes are hard to come by in this market, we are looking at homes with walkout basements and are assuming a $50k-$60k cost in converting the basement to an apartment.   I'd love to know what other investors and realtors think of this strategy.  Is it smart to spend the money on creating another living space and what would it do to the resale value of the home?