I have a number of affiliate sites up on the web. I have tried paid advertising to get traffic by way of PPC. Its like throwing good money after bad.
Every now and again I pick up some free PPC from Google /Bing and try but it does not yield much.
Some time ago I did pay for some some inclusion in other peoples email lists which brought better than PPC results.
Some folk try Facebook ads. I've not tried it and would be interested to hear if anyone has had much success.
Unfortunately the only way I have found to get traffic is the hard slog way - frequent Posts, backlinks, Dmoz, twitter and getting friends to share on FB.
I did also buy some traffic on Fiverr - waste of $5.