I think it depends on what kind of traffic that you highly directed downloads.
If there's a lot of tier1 countries that have high buying power, I see it's as high as $3 - $5 CPA. But if it's blank installs or lower quality, I saw it's down to $0.1 - $0.3. They even allow incentivized traffic in this case.
We can chat more about this on Skype if you like