As I've noted before, the annual federal subsidy to PBS is $444 million. That's 0.012% out of an annual $3.5 trillion federal budget.
Put another way, let's say you earn $50,000 per year and you suddenly needed to cut back on your expenses. So you trim 0.012% from your annual spending. Congratulations. You'd save a massive $6 per year, or 50 cents a month! And now let's say you announced this brilliant savings plan to 60 million viewers on national television. The audience would rightfully think you were a crackpot, and you'd likely be laughed off the stage.
So how did Mitt Romney get away with it? (By the way, the president isn't blameless for letting him off the hook.)
Adding... While we're at it, if it took you longer than 15 minutes to devise this savings plan, you will have spent the $6 you saved just on lost wages.