Advertising - Where do you see or hear it? (this is not an ad)

I'm a dispatcher/media/computer/everything guy at my dad's company that has 10 dedicated owner operators that run strictly with us. We've had a lot of these O/O running strictly with us for 8+ years, but my dad has been interested in trying to find more. At the moment I've been posting ads on Craigslist, but we've been attempting to find other methods of advertising.
We've looked into gas toppers, newspaper ads, and other similar media, but everything is incredibly expensive once you go outside of Craigslist. I was wanting to hear from owner operators where you guys see or hear advertising, maybe some stories of advertising working for you. We've had a little luck with Craigslist but nothing that has turned long term with the people who have inquired.
If anyone has any stories about how they were recruited or know of any ad campaigns that panned out for them I would love to come back to him with some avenues we may be able to pursue. Thanks in advance!

 

We pay a consistent fair rate year round and treat our drivers with respect, which is why the ones we do have have continued to be with us for so long.
Really my question was more geared towards exposure. How do you even hear a company even exist, or that they're looking for O/Os? Which avenues to go down to get our company exposed is my main question I guess.

 

It sounds like word of mouth may be our best option then. We've offered bonuses in the past to our O/Os who were able to recruit others for 30 days or more, maybe its time we run that campaign again.

Thank you everyone for the feedback.