Parts list for a planned Harman Kardon retro-fit

I'd like to work up to retro-fitting the Harman Kardon audio kit to our 2011 R56-S, by buying the parts as they come available on eBay etc, however I'm drowning in a sea of possible components. I'd hoped to find a way of using https://www.realoem.com to list out the parts I need & ideally their part numbers, but I can only ever seem to get the site to display diagrams & parts lists for the "HiFi" audio option, not Harman Kardon.

We currently have the Mini Navigation System fitted if that has any relevance to audio and from reading-up on the subject here I believe I will need:

• Harman Kardon amp
• The amp holder/bracket
• Front A-pillars with speaker grilles
• Front A-pillar tweeters
• New Door cards to allow for the additional front speakers
• Other speakers (!)
• Speaker brackets?
• Suitable wiring

Can anyone point me at a slightly more detailed parts list than the one I've created, please? ;-)

Or any used parts suppliers who are likely to carry the bits I need.

Thanks,

Steve