No one has taken me up on the offer. Which was my intent. The point of that extra charge is, I don't want to do that work. =)
And the easiest way to have a client not make you do something is to charge them extra for it. It just makes them think "Do I really care enough to pay for it?" And if that answer is yes, I just have to make it worth my time and sanity. But if you offer them something for free of course they'll take it.