Well, that's the MorphOS lot for you. There is a lot of rivalry between the two "camps", and it seems from the forums that the AmigaOS and MorphOS lot don't get on too well. Ignore the bickering, flamewars etc and the only place to discuss both in relative peace is here on amiga.org (ann.lu is a flamefest, and the other sites are pro-AmigaOS or pro-MorphOS and woe betide those who mention the other)
Anyway, my advice:
If you want to upgrade, and the PPC cards really are that cheap on eBay, then get one of those and then you'll be able to run OS4.0 BPPC version when it is released, which will be PPC-native and will fly on even the slowest BPPC card.
If you like it and the software support starts to return, you can buy an AmigaOne in the future (such as the MicroA1 which hopefully should be A500-type pricing once it goes into mass-production)
Chris