One of Sega's many "doomed" systems released between the slow death of the Genesis and the release of the Saturn.

It was a Sega CD the size of a doubly-thick cd player.

Cost around $300 on release, but worth it for its portability and enormous game library. Less worth it if you already own a Genesis, and worthless if you already own a Sega CD as well.
Who would buy this except someone who already owns and loves Genesis games? And who would re-purchase a console they already own? This system was really just an eccentricity, and was released in only in small quantities.