I have been playing a year and 2 months. I have 5 tier XI characters, and another 16 tier X. Plus a handful of tier IX as well.
I spent $100 on the game in that time (I wouldn't have spent even that much, but there were.... extenuating circumstances). None of that went to gear purchases in the shops. Have been running heroic rancor raids since near inception. Have only been doing normal ATT raids.
So you are severely over estimating the time (assuming you can do at least H Rancor). And/or you aren't spending enough energy on farming the specific gear you need for your characters right now.
