"All traffic is good traffic if you know what you are doing" -- u-Bob, 1935
Personally I'm still buying traffic and turning it into a profit.... how? by analyzing and filtering my traffic....
anyway, the price drop could also be related to the increase in supply. More people started selling traffic for a guaranteed price instead of sending it to affiliate programs because conversions went down (because of traffic leaks (think twitter), because of ancient tracking methods (think cookies), xsales and js exit pops on revshare links,...)