I can get 100 people per day to make my survey, but only from Slovakia

Hello BlackHatWorld.
I just find out that I can get from 100 to 500 people per day to make any survey.
But there people are from Slovakia only, so which networks are best for me to began using this method?
Thank you

http://www.offervault.com/

there i think you can search for cpa networks that support specific country