Seems unbelievable that they can sell those cables (FGTech) in the $50 range, and actually make any profit. They will read and flash quite a few controllers - including GM's 512Kb and 1Mb PCMs, E38, and E67. The latest version may also cover the E78 and E83 ECMs (not sure).

As long as you have an old computer that you will never again connect to the internet, and you don't mind the Trojans that come with the software, these are likely the most economical means of getting the job done.