If you do a search on "Saturn Rafts" or just look below, you'll find a lot of info on them. Personally I wouldn't want one even at the price they're going for - I've heard they don't bail quickly because the floor seals against the tube and blocks the bailing holes, and have heard they're not well built. That said, depending on the intended use (fishing on Class II?), one may be perfect for you.
Nothing in the world is more yielding and gentle than water. Yet it has no equal for conquering the resistant and tough. The flexible can overcome the unbending; the soft can overcome the hard. - Lao Tse