Currently there are several apps on sale that are essential apps for any musician who wants to make music with their iOS device.
First – This one is just a no brainer, if you do NOT have this app then get it now. AudioBus2 is THE app that has opened the doors to amazing new possibilities with music making on iPads/iPhones/iPodTouch. AudioBus2 allows one app to pass audio off to another app and even lets us throw in a 3rd app for effects in the middle! This allows you for instance to use a DAW, such as Cubasis/MultiTrack DAW/GarageBand, to record the audio from a synth app like Thor PolySonic Synthesizer.
Speaking of Cubasis…. IF you really want to get serious about recording audio AND MIDI on your iPad then this is the app for you! Even if all you ever do is record audio from outside sources and other apps then this is probably the app for you! It runs much better on an iPadAir than it does on an iPad2 though. If you are still on iPad2 then maybe you should look at MultiTrackDaw.
Cubasis is on a 30% sale – down from the normal price tag of $49.99 to costing you only $33.99 currently. When an app that costs that much is on ANY kind of sale like this you should grab it! Cubasis is a serious step up from GarageBand, the options this app will open up for you are pretty serious! Which explains the price tag. I would NOT suggest spending this much money if I myself did not use the app (for which I spent my own hard earned money too by the way)
The last app right now that I want to mention is Thor PolySonic Synthesizer. This app is only on sale until tomorrow, the 31st of August. It is one of the most amazing synth apps for iPad currently. The price is only $4.99 currently which is 66% off.