Here's what it says in their FAQ about promo codes (I have no idea what it means, though...):
"What is a Promo Code and where do I get one?
The promotion code is only needed when ordering from a sale advertisement in a magazine. If there is a time that you will need to use a promotional code to receive a special price we will inform you through the advertisement, email or in the catalog."
Come to think of it, I ordered their catalog weeks ago and never received it and I don't know why. Do they only have online catalogs now, not hard copies?