My ignorance always assumed the guys at efi live, as you said, play favorites. I now have a whole new view on you professional tuners . I wish I were mart enough, and had the equipment to hack ecm's and find new tables. Man that'd be cool.
I did it with nothing other than a flash scan and an obd link lx, and 010 editor.
Granted someone did supply me with reads for all the years and versions. Still, that's under $1000 setup. If you're really clever you can push that down to $100 with just an obdlink. And if you are ridiculously clever, around $5 for an STM chip.
I wouldn't recommend new people to get into it though. Future is not bright enough.