I brought a 2GB sd card (by ultra) for $12 including shipping
it has a max red/write speed of 10.2MB/s
and with it, on a canon powershot a560, I can take images at 2FPS or about 1.4-1.5 FPS for camera raw (using hacked firmware which unlocked the camera raw features)
and while using a 1 gb sd card which offered a faster read/write speed, around 12MB/s, the speed of taking pictures did not improve at all
I think the problem is that with point and shoot cameras, the processor in the camera is not fast enough to rapidly take photos and and save them at the same time, only the high end non slr and the digital slr cameras are able to do this
the best thing to do is to read the reviews of the cards but instead of looking for reviews about speed, look for reviews about how quality and how long the card will last
PS raw images if your using a hacked firmware on your canon, is usually around 6-7 MB in size and depending on the hardware in the camera, the images may be around 10-12 bits instead of the 16bit images of the high end digital slrs