In case it's of use to anyone, 3.0.2 is still available on Amazon, there's just no link to it.
You can get it by replacing the '3.0.3' in the URL for downloading the latest firmware with '3.0.2'. So to get the Wifi version, go to:
https://s3.amazonaws.com/G7G_Firmwar...3.0.2_B008.bin
And for the 3G version:
https://s3.amazonaws.com/G7G_Firmwar...3.0.2_B00A.bin