you may be better off trying to repair your existing one (assuming you have a dead one, and are not trying to put together a frankinmac). Try and find someone who can diagnose the failed component and have them replace it.
Or just go to the components section for Apple's on ebay and look at the list of powersupplies available for the quicksilver.
* Home >
* Buy >
* Computers & Networking >
* Apple Computers >
* Apple Components >
* Power Supplies
You may also be able to hack on from a Digital Audio or Mirror Drive Door since they have the +28V leads. You would just have to swap some cables around since the pinout changes.
I think the MDD one has a higher wattage rating than the Quicksilver