I bought both my 16 gig class 6 cards for $29 each. If you have a Frys Electronics store near you, you can catch them for sale every 3-4 weeks. The brands are Kingston and Patriot. Don't buy them from their online store because they kill you with the shipping.
I don't have a Fry's store here in Hawaii but I have a friend get me one in California when they are on sale. Then he drops it in an envelope and send it to me for 42 cents (instead of $10-$25 shipping cost).