Taffy, let Shiny send you a link to her photos. She is the queen of cardis and has shown us some excellent combos. A cardi is so versatile, you can wear it open or partially closed for waist definition, and you can add a belt over it for some extra oomph.
I myself didn't own a cardigan until about a year ago, either. For some reason I considered them too classy/conservative. I was very wrong Angie first suggested them to me, and then I saw all these great outfits on YLF with cardis and let myself be inspired. I now own several long-sleeved ones and one short-sleeved one, and wear them *all the time*. BR and J Crew have great quality cardis in nice colors. Zara (if you have one in your city) has decent quality ones for cheap.
Of the BR colors you linked to, I love the turquoise and the purple. I don't know what you look like and what shades of blue and green you wear a lot, so it's hard to say whether these would be good colors for you. You can also try yellow (I realize the BR cardi is not offered in yellow, but maybe some other cardi is) to go with your blues and greens. And cream would be a nice complement as well, and "safer" than yellow if you don't want to be too bold at first.
