SFR w/ Basement or Duplex?

[Thomas Taylor III]

 Hello All,

 My friend and his wife just got married, and are looking for their first home.  They would like to buy a duplex, but we have ran into some issues as I have helped them look in the Salt Lake City area.  Duplexes are incredibly expensive here, hard to find, and the ones that are available receive nearly a dozen offers $10,000+ over asking price within the first few days.

 What are your thoughts on buying a single-family residence with a mother-in-law entrance, and renting out the basement?