Trying to comprehend the bazillion materials I need to complete the several ascended items I want was driving me quite insane, so I did what I do best; complain on the forums make a spreadsheet! 
Just make a copy of this spreadsheet to your own Google Drive, enter how many of each item you want to make on the right side, fill in the material boxes with what you have, and enjoy the delicious data. 
It’s currently pre-loaded with my own data so you can get an idea of how it’s used. (donations are welcome, of course. 
)
This sheet makes use of my nifty GW2Spidy library for Google Sheets to fetch prices from GW2Spidy. You can change whether order or buy prices are used by editing cell V1. The cell notes should answer any questions I’ve preempted.
For each item, this sheet does count the materials required to make the Inscription/Insignia, but it does not include the Exotic Inscription/Insignia.
Let me know what you think, and enjoy that grind ahead of you!