"Substance" volumes 1, 2, 3 & 4 are now available in Google Play. Each expansion pack costs $1.25. There is also a free demo for each pack to try.
Loads of new Beatbox kits and PCMsynth patches (most have been multi-sampled). Bass, leads, pads, synth percussion, guitars, strings, and keys.
Link to Google Play: http://bit.ly/JavdrN
Demo of Beatbox kits: http://youtu.be/8KEXWb0zjEE