it may be awhile, but sunremarketing.com carries used mac parts or hard to find parts for the mac and i used to refer people to that site and overall, they were happy
since your G4 ibook is so new, if you can't get it from apple or an apple dealer, you may have to wait a few months before sun remarketing will get those...and i know that can be a bummer
but good luck on your search and being a tech and engineer, i totally empathize with you when it comes to finding apple parts