I can't beat it, but I got an unusual tip once... The guy was the editor of a small newspaper, about 6,000 paid circulation. He told me they often have 2 col. x 2" (basically biz card sized) ad holes in the paper for ads they expect to be purchased, but at the last minute it is cancelled. These could be purchased for 1/2 price, about $15 for that size if you wanted to not be guaranteed position or even if it will run, you just had the ad ready and prepaid for it. Eventually it would run...
About 2 weeks later I sent him a small ad and a $15 check. He ran the ad twice so far, and he mailed the check back! So far it generated one job and several calls, but it is easily overlooked because it is small, but free.