Search Ebay for it. There is the possibility for searching for "ended auctions". The green ones were sold, the red ones were not.
I could tell you, that here you get 1-5EUR for it. Better idea: part it out.
Sell the 400MHz G4 ZIF CPU to a PowerMac G3 B&W owner as an Upgrade. One reason why G3-PowerPC owners upgrade the CPU is, that it allows for using higher versions of iTunes.
(Ebay offers events - don't know the english counterpart - where you can start auctions with a starting bid higher than 1,-EUR free of fees. Maybe you have that too over there? CPU Price ranges from 1-15,-EUR here!)
Sell the Case (gutted out) for modding. Use keywords like: Hackintosh and case modding in the article title.
(5,-EUR here, crazies pay 20,-EUR here)
Sell the ATI 128Rage PCI for people who want to add a second display, but have low demands. People also can use them to have a working monitor output, while flashing a PC-AGP card for Mac (which they would have to do blindly otherwise).
1-7,-EUR.
You can put the other parts together in a package, or if you have time: put them all up seperately and sell them for 1EUR each (despite the optical drive, if it is still the old CD-Drive).