PPC Traffic Ratios - Why Do They Differ So Greatly?

So a month or so back i actually dropped AdWords traffic for in house sales and instead went with Yahoo and LookSmart and i must say, the difference in both cost and click ratios are simply put, amazing.

It cost me almost $20 in clicks to make 1 sale from Google AdWords.

Its currently costing me $2 in clicks on LookSmart and $4 in clicks on Yahoo to make the same 1 sale.

All 3 places used the same title and text on the ads yet its costing me 10x less on other PPC placements than at Google and im making the same number of sales.

Has Google really killed PPC traffic that much?

Regards,

Lee