Have you ever thought of using cross-mobile software platform ?
I run a software company and we are using such tool most of the time.
It allows to break the cost and the headache to maintain multiple versions/OS and is very helpful for maintenance and upgrades.
We use a software who generates native mobile code and allows to have a unique UI which is generated through this product.
Then it generates native source code according to OS/version/device (more than 1000 devices are supported).
It automatically manages tablets or smartphones display with appropriate UI.
The master is coded in Java, very close to Android, with a specific API.
If some specific code or library is needed the product allows to insert such code for a specific target.
I am not trying to sell anything and I haven't any shares in this product, just sharing my experience.
So far we have successfully managed more than 20 projects in the 20k-100K range.
There is a site which lists and evaluates cross-platform mobile development platforms (including the one we are using):