With Android M scheduled to be coming at the end of the summer, you can get started developing apps for it (and other Android version I'm sure) with this course using Android Studio. Prices start at $23 with lifetime access starting in July. They claim this course is for amateurs & experts.
Here's the link. If you take this course, let us know what you think.
The Complete Android M Developer Course with Android Studio by Rob Percival Kickstarter
Tapped from a Nexus 6
Here's the link. If you take this course, let us know what you think.
The Complete Android M Developer Course with Android Studio by Rob Percival Kickstarter
Tapped from a Nexus 6