4GB SD Cards
If you're looking for a 4GB SD card, but you're overwhelmed by all the choices available, this little comparison guide should help make your choice a bit easier. Please note that all prices could change at any time, and you should expect the price information in this guide to become outdated at some point.
Class 6 is currently the highest speed class available in SD cards. Don't go for a Class 4 or lower card unless you're really on a tight budget and speed isn't that important to you.
Class 6 SD Cards
Transcend 4 GB Class 6 microSDHC Flash Memory Card TS4GUSDHC6 - $9 (Personally, I'd go for this one. Why? Well, Transcend is good, and also, it's a microSD card with adapter, so you can always use it in something smaller if you ever need to, like a cellphone or something. Just an extra little handy ability.)
KingMax 4GB High-Speed Class 6 SDHC Card with Free SDHC/SD/MMC USB Card reader - $10 (This is also a nice option if you want a USB Card Reader as well... although I don't really trust KingMax. Had some dodgy RAM made by them at some point. But maybe they make better SD cards...)
Extra Fast Class 6 Cards
If speed is really highly important to you, you can consider a Class 6 card that also has extra speed boosting features built in as well. Here are some super fast 4GB SD cards you can decide between:
SanDisk Extreme III 4 GB Class 6 SDHC Flash Memory Card SDSDRX3-4096-A21 - $18
SanDisk is one of the original developers of SD card technology, so they probably know what they're doing as far as manufacturing them goes. But Lexar isn't a bad brand either. Price wise, SanDisk wins here.
Really Really Cheap SD Cards
If you don't mind going for something a bit slower, you can get this card:
I'd list more class 4 cards, but they're kind of old now and will probably stop being manufactured at some point soon.
What do you think? What 4GB SD Card would you recommend?