Free?

At my job we have to try and give out these savings cards called Pet perks cards. Basically like a grocery store savings card that you can stick on your key chain.
My schpeel goes about like this after asking if they have a card and they say no...
"Would you like to get one? It's free and it gives you savings on certain items in the store..."
The first question by more than 50% of the customers...
"Is it free?" or "How much does it cost me?"
Gotta love it.