I agree with you. It's far too expensive, and I doubt you'll find too many Amiga users who would disagree. It's a way of keeping the platform alive while the problems with Amiga Inc. were sorted out though.
The decision to go PPC was made way, way back when there was a lot of money around, and m68k -> PPC made the most sense with regard to endianness.
Since then, with the contract with Amiga Inc, and all the legal difficulties, Amiga OS has been effectively nailed to PPC.
I remember reading that the developers would love to port it to x86 if they had the resourses, but for the moment it's PPC only.
For a couple of cheaper Amigalike options, the Amiga OS compatible MorphOS has just been released for the G4 Mac minis, and the open source AROS (in the form of Icaros Desktop) is available for x86 hardware.