I had a similar experience with Weathertech... Ordered a set of mats for my wife's car this summer. Somehow, despite several 'verify your order' pages, I ordered the wrong color. I called customer service, explained what happened, and figured I'd be on the hook for shipping the new ones in the right color. Much to my surprise, they issued the RMA and said that as soon as they receive them, they'll send the right color free of charge.
They did exactly that! My error cost me $11 to ship them back and nothing more. Couldn't be happier!!