I Believe the other members are correct you could send it back to them and pay for it to be upgraded.
Apprentice sabers would be harder to do because of the smaller hilts, there was a discussion recently on that topic Best DIY Hilt
As far as doing it your self as long as you are decent with a soldering iron, heat shrink and good with you hands then it would not be too hard to do yourself many people have wiring diagrams showing how to do it for every sound card you can think of. For your first time i would pick a simple sound card more basic like their saber-core soundboard, Naigon's spark, Plecter labs Nano Biscotte, or Petit Crouton they would be easier for first time. If you did get a 12w warrior you would be set with the Li-on battery you would need for upgrading sound.