Need an SD card for Wii stuff

I need to get some sd flash memory so that I can transfer things to my Wii, I actually already have a few SD and Micro SD cards but they both have things on them and it needs to be empty other than the Wii .wad files for doing what I want to do – I suppose I could transfer the things already on it to my computer, and then back once I am done, but it seems like less hassle to just buy a small one — they are cheap enough these days!