I've seen a few un-opened CD32s up for auction, but they are certainly not currently being manufactured as far as I'm aware. However, I don't see a problem with s/h, but you must take into account what condition it may be in (pictures of what you're buying help a great deal here, especially if it's shown running a game). I would imagine the most likely component to fail to be the CD drive mechanism, but I've seen places that still sell such parts.
Also, set a budget for how much you're prepared to pay given the condition, controllers and games included (games like wing commander, dangerous streets, oscar + diggers, cannon fodder are so common it's not worth worrying about)... unless you really want one and don't have a limit.
Finally, make sure that if you're having it delivered that it's packaged well (preferably in the original box / polystyrene), 'cos it would be so sad to lose one by the hands of a courier.