Buying traffic to make money from popunders is not a good idea at all, as you wont even get close to what you spend. If you spend money on advertising though, try different options like:
Adamo Ads
Click Papa
Ero Advertising
Exoclick
Traffic Holder
Juicy Ads
See what works the best and go with that. If you want to measure the results it sounds like Google Analytics and all ad networks should be able to make it work with that. If not, they have their own dashboards with all the info that you may need.