Download Firmware Files
Firmware files are zip archives (but have extension .ipsw) and are fairly large. Your iTunes may have some of them already (if you have ever restored) and iFuntastic may have some of them as well.

The iTunes files are kept in [user]/Library/iTunes/iPhone Software Updates/
and [user]/Library/iTunes/iPod Software Updates/

iFuntastic keeps its copies in [user]/Library/Application Support/bitSplit Enterprises/iFuntastic/IPSW/

You should never have to manually download them, but if you need to, then you can do so with these functions. The files are downloaded from Apple, are available at their discretion, and are their intellectual property.

The firmware files which you can download are:
Upon successful download they will be put into the iFuntastic Support folder (see above.)