For C= stuff, its a tie for the ultimate, cost-no-object, dream machine. Either an original NIB A3000T or an ESCOM A4060T (though I'm not sure if this qualifies as "C="? But, if it is permissable to broaden the category a little bit, I think its also worth mentioning another ultra-rare digital "objet-d'art" that would surely fetch in the several thousands of dollars if one were ever put up at auction. That would be the super-sleek Atari STbook, the modern laptop that was made many years before laptops (or even desktops for that matter) became "modern".