Have you look at Applift, Kissmyads, Clicksmobs, Yeahmobi, Offermobi? They pay per conversion. Some of them is simply pay-per-install by platform/country, but some has deeper conversion.
We are running AdsOptimal. It detect platform/country and serve the offer with mobile-optimized layout. It gives extra $2eCPM on top of what the site already made. Feel free to skype me at badd.th if you would like to chat further.