Well, your best bet is probably Ebay, or even just Googling. Lots of the import sites still sell them. I'm not 100% sure, but I think the region-free PS2's can play it as well, so I'm personally going to at least try to get one, so that I only need one PS2 instead of two.
My original Jap PS2 was one of the bigger ones, and the scream of rage when it got the Disc Read Error still echoes through time. I NEED MY GODDAMN DARK AEONS
Ed: on the other hand, you can also download the PS2 emulator onto your comp and play it that way, although your framerate is going to taaaaaaaaaank. /personal experience
I really wish I could find a site to host my videos, so that I could actually CONTINUE that Let's Play... *sigh*