I see that you didn't get an answer yet, i'm not from Airpush, but I can help -
According to what I know, from devs working with us, Airpush has very high CPM (around $12), but a lot of people don't like their solution and give a lot of bad reviews to the apps.
If you are still after a monetization solution, please email me at - ariel@startapp.com
We have an interesting model, that pays per download to the developer, I would love to tell you more.