I don;t think you need that much of space or you should spend that much money most of the services like skydrive and dropbox allow you to save files online so you can access your music from anywhere even 32 GB will be good for music and apps you are running going for 128GB will be only waste of money in my opinion rest is all upto you to decide.
I have a 16GB iPad 3 and so far I'm doing good as far as the apps and music that I want.
Current Apple Devices:
iPod Touch 4th Gen-Black-8G-WiFi
I have a 128gb iPad 4, so pretty big NO from my perspective.
The wife now use my 16GB iPad2 and it is still enough, but she does not use it for photo's or music. More is always better, but less mostly require just a little cleanup and housekeeping.
Sent from my iPad using iPF
Sent from iPad 32Gb 4G/Wi-Fi via IPF