[iBook] Buying Panther install CDs

[Peter Nevett]

This seems like a silly question but where can I buy install CDs for 
Panther (OS X 9.3)?
Is it possible to buy and download?
I live in Mexico and my nearest Apple agent tried to install Panther on 
my wife's G3 Blueberry clamshell (currently running OS 9.2.2, 320MB 
memory, 2.42 GB available on the hard disc).
Is there any fundamental problem with upgrading to OS X on this machine?

Pete Nevett