It's pretty much random whether the cheap or the expensive one is good. There are times when both are lackluster & times when both might be worth it.. so, yeah.
Guide for using JP wiki
1/2 - https://youtu.be/hPK8vpqmkCg
2/2 - https://youtu.be/GhvZJXjngO8 Y U NO WATCH 2ND PART!?
https://docs.google.com/spreadsheets...it?usp=sharing
Finally, I can share this!
This is an Advent Calculator that I created and recently updated with the new exchange prices. I created it to know about how many runs and HEs I would need to use to collect all the items I desired. It works best with Ultimate runs, because that's the only one I run and have drop averages on. If you know the average of drops for other difficulties you can manually enter the drop rate.
I use it all the time and it works quite well. Anyways, I hope you guys find it as useful as I have. There is video instructions linked on the front page and instruction comments all throughout denoted by the black triangle in the upper right corner of a cell. Just hover over the cell and they will appear.