I mean I was assuming best case scenarios. I don’t recall having issues completing a vision (as far as was required for the quest). Certainly not if you do it in a group.
A fresh alt requires essences for the neck. There are 4 at 2500 a piece = 10k. Check the vendor they are only 2500. Essences are the 8.2 power mechanic not corruption. Not sure where you are getting 2750.
I also low-balled it saying you only need 4 if you are focusing on a single spec in order to give these nay-sayers (“its fine”) the best case scenario (least expensive).
This doesn’t take into account the major/minor assaults you would need to get enough coalescing vision currency to even run the horrific visions in the first place. Those major/minor assaults also grant echos.
As to the vision echo total - I went with numbers assuming you were only getting as far as necessary for quests - so not full clears from rank 1. Your mileage will vary if you can push further given your class (or carry).
You can find my walk-through here. I recognize it isn’t perfect.