We use Transcend cards and we buy them from Amazon. I don’t often shoot at 720, but at 1080 we can get about 1/2 hour on a 8gb and almost an hour on a 16gb card. The nice thing about these cameras is that it switches automatically from one card to another when the first card is full. It is seamless, so you don’t lose anything. Also, while the camera is recording on one card, you can eject the other if it is full and replace it without a problem. In this way, you could feasibly record till your batteries die or you run out of media.