Yeah, eBay. They're virtually giving Saturn stuff away on eBay.
As for variations, I think it was the Hi Saturn that came with the VCD card built in. Not too useful these days, but supossedly its the best quality VCD card for Saturn, and only came with the Hi Saturn. Other than that these "3rd party" Saturns (not really a good term for them, IMO) are the same as the white Saturn, US 2nd model black Saturns, etc. They aren't really worth any more or less than other versions of the system, and as such they don't cost any more.
I'd go with the white one, which is the coolest one anyway unless you have the scratch for a Navi, and even then...I think the white one is cooler. I mean, what I'm I going to do with massively outdated GPS software that only works in Japan?