I too am a registered user of Logic Pro 8/Logic Studio 1. I recently bought the upgrade to Logic Studio 2.1 from eBay (from a company that has surplus boxed left-overs, authentic and new sealed, for a lot less $ than what you saw on eBay BTW). However, the version I got in that box is Logic Pro 9.1.1 so it is far beyond the 9.02 that you need for a PPC Mac.
I think that by now, all the boxes bought up by surplus vendors from when Apple closed them out will all contain more updated DVDs than what you need, because when Apple stopped selling Logic Studio boxed, the discs had already been updated, like Blueberry said.
Unfortunately on the discs it does not state what the version of Logic is, so you'd have to find some selling theirs (who have already opened their boxes and used the discs) who could actually tell you what version is on the disc. But the problem with buying someone's used item is you'd have to somehow make sure they really did deactivate it and are not using it anymore NOR are they going to use that serial number when it is time to upgrade. That's why buying it new is the best way, and there are still legitimate new ones on ebay when you look... but unfortunately they are newer versions than what you need, I'm afraid.
FWIW, my box says MB798Z/A LOGIC STUDIO V2.1 UPGRADE PRO, so it is NOT what you need.
Sometimes, if you know of a little mom-and-pop music store that doesn't have a fast turnover of software, you can sometimes find really old software that they weren't able to sell. Also some stores going out of business, or liquidators that bought out the merchandise from them.