Maybe. The best source would be Apple. Contact them using the phone number in the Apple Online Store and explain that you require a replacement set. The biggest obstacle will be finding someone that understands what you need.
When you eventually speak to someone who asks for your iBook's serial number, you'll have succeeded: Locating your iBook Serial Number. Unfortunately that document is not very helpful, so examine its case for a likely number.
A distant second best source is the used market, eBay, etc. The disc you require must correspond to your exact iBook's model designation. Its will be either PowerBook6,3 or PowerBook6,5 or PowerBook6,7. If a seller cannot confirm that information keep looking. Good luck!
Ebay in the u/k, I have seen them, have to disagree with john galt, as a owner of ibook g4 tiger 10.4 cd you are looking for must be for ibook g4 2 cd' required 1&2, this will take you up to 10.4.11, after this you will require leopard which will take you up to 10.5.8 the maximum you can go to with be ibook, hope this helps robin u/k.