You don't need any extra cables for the amp, if he means to amplify the signal you can do the 'Buster hack'
Also you only need the '29' steering patch cable, the '007' is the older mode and not requiredl, so over £100 for cable is steep you just need the bose loom, the steerping patch cable (29) and the fascia, the 'Buster hack' doesn't require any extra cable at all but will probably be needed or the volume will be very low.
It's not a terribly hard thing to do you just have to be very careful and make sure you do everything exactly as in the guide :thumbs;