This is very insightful information. At the pricing levels of these services, it doesn’t suprise me so much though that you didn’t see a big increase in downloads.

We’re running a CPI (cost-per-install) app promotion services and in some countries lots of advertisers are happy to pay $1.50-$2.00 for getting an app install. (See https://www.appbrain.com/stats/android-cpi-per-country for actual prices). If a $69 or $49 investment would give you 100+ installs, that would be a very cheap way of promoting your app.