Despite Tim Fox's putting a fine twist on the history of the phrase, I still contend that "too cheap to meter" as a cynical response to the optimistic "promise" of nuclear power is the appropriate one. That condition was never to come to pass, as the geniuses who saddled us with that technology never did their homework concerning the costs of the technology, including all the ancillary, hidden costs like those associated with the nuclear-fuel cycle, especially concerning things like waste disposal and plant decommissioning.
Which, BTW, is the real reason most places are hesitant to adopt more nuclear power generation: not so much the result of the agitation of people like me (I was an anti-nuclear activist in a former life), but simply the economic aspects of that technology. It just doesn't pencil out, despite Bill Gate's, et al, efforts to revive it with the "next generation" of reactors.