It's not an ouch. The 550C is rare as hell. It was only released in Japan and has some nice upgrades over the rest of the 500 series Powerbooks.

The seller mentions in the listing that it was only sold in Japan, so they did know what they had. 550C's don't come on the market from people who don't know what they are. If someone had it shipped over from Japan, they knew exactly what they were buying.