Trying to find a duplex to buy.

I'm having trouble finding one online because all the ones listed seem to be bad deals or in bad areas. I'm trying to find out how to find a good deal and what aspects of the location to keep in mind. Should I try to find a brick building or is wood okay? I have around 65k in an account. What's the most I should pay or lease one for and what is the least amount I should lease one for before I'm just getting junk. What things about the areas I'm looking for do I need to watch out for? What kind of places are more likely to have duplexes for sale as opposed to single-family units?