Well there are a few bigger ones that can drive traffic Bing Ads : https://bingads.microsoft.com/ https://bingads.microsoft.com/ Facebook ads : https://www.fa

Well there are a few bigger ones that can drive traffic Bing Ads : https://bingads.microsoft.com/ https://bingads.microsoft.com/ Facebook ads : https://www.facebook.com/advertising‎ https://www.facebook.com/advertising‎ Yahoo Ads; http://advertising.yahoo.com http://advertising.yahoo.com It really depends on what you are targetting, ie. you want to target based on location, interests etc. Also you should start to expand your keywords on AdWords, try split tests of different texts and see if you can bring your CPA down.