Where can I buy the most cheapest mobile traffic?
Why do you want to buy cheap traffic anyway? They doesn't contain any quality.
Yahoo Gemini or Vazu may be good options for you.
Buzzcity and admob are also good ones.
Yahoo Gemini, Airpush, Buzzcity are all good options. But why do you want cheapest traffic anyway? The quality of that traffic will be low for sure.