You don't need any particular type or brand. I do recommend Kingston- they're widely regarded as some of the highest-quality memory regardless of product, and flash memory is dirt-cheap.
Alternately, go to dealnews.com every day or two, and check the "Photo" section (which is where SD card deals appear). If you wait for a few days, there's always something ridiculously cheap there.
FYI to those interested, I got a SanDisk 8gb micro sd card through Amazon for $17. Pretty good deal. More memory than I"ll ever need for an 8330 but oh well.