So, I stumbled across a guy on my arena shard that had every character in the game (yes, including Colonel Starck, Wampa, and Probe Droid) fully-modded at G11, with more than half of them at G12. Ever...
Depends when played from. A lot of the extreme cost is playing catchup. Many players have full rosters with all the farmable toons gathered organically. Then it is circa $700 a toon to unlock and gear with just cash.