In retrospect, it’s not surprising that Big Bird is currently the nation’s top selling Halloween costume. Other than Obama and Romney masks, nothing else is particularly timing, and who wants an Obama or Romney mask? Big Bird all the way, if you ask us, and America agrees. Since the presidential debates, the sales of Big Bird costumes have seen a 500% increase, presumably owing to Mitt Romney’s promise to cut government funding to PBS. Meanwhile, Jim Leher costumes remain sadly overstocked …