Is there an open-source alternative to Manga Studio?

[Ariii]

Hi! I used to use Manga Studio for some things that I've done before, but the disk I used to install it was Windows only, and I switched to MacOS 9/OS X a couple years ago and now have a better use for it. For most things, I've found an open-source alternative that works well enough, like AbiWord, etc., but I can't really find one for this, and I'm hesitant to pay $50 to get it. I have found one good program, but I don't know enough Japanese and it was Windows-only. I can't use Wine either because I use a clamshell iBook and a PowerBook G4. Is there anything else out there?