Goclick is the cheapest one but also have the highest click fraud rate or in another word you will get the click but not the conversion.
Hi sodahouse, If you go for the cheapest clicks you are probably getting fake traffic. A better question would be to ask "where can I get the highest ROI" (Return On Investment). Getting the highest ROI is primarily a result of well done keyword research, well written ad copy and the use of an ad network with high quality traffic (AdWords, adCenter and YSM). You can buy cheaper clicks from other networks, but in the end, they will usually cost you a lot more.
There are quality low cost ppc. I can tell you that in my case Adsense pays me significantly more for the traffic that originates from some of the secondary ppc companies than it does from Adwords. But be careful, there are definitely some scammers in the low cost market.
heres to of the best i think http://www.ad-cents.info/index.php?ref=jyale http://www.ptcdepot.com/index.php?ref=jason
the best ppc that gives you less than 0.157$ per click are the ptc networks and i'm launchin my own ptc website realptc.eu and click prices are less than 0.01$ per click for a 30 seconds ad interested ? realptc.eu/advertise.php