What is the best ways to find new properties to purchase?

[Justin Wood]

I own 13 rentals, and I have been searching everywhere for another one. But the real estate market is great right now. And when it is great there are no cheap deals. All the prices in my city have been driven up. I need to find houses for $130,000 and below. But where? 

What have you seen work to find deals? Mail postcards? I buy houses signs on corners? What are the best strategies that have worked for you?