You don't need anything as fancy as Logic as an AU host. The cheapest one is AU Lab, part of the developer's tools that come with your Mac. I don't kow how well it works. Garage Band also hosts AUs, but I've never tried it with anything serious. Or you could just buy a copy of Logic Express.
Steinberg V-Stack (I think it supports AU as well as VST), Plogue Bidule, and plasq RAX are others. Native Instrruments KORE looks interesting, altthough it's more expensive than the others.
Steinberg V-Stack (I think it supports AU as well as VST), Plogue Bidule, and plasq RAX are others. Native Instrruments KORE looks interesting, altthough it's more expensive than the others.