Oh, I just have an excel that uses all the current ship prices as input, just got to keep it up to date.
Then whenever I purchase a CCU I just put in the ship from, the ship to, and what I actually paid for it. The excel will show the from price, the to price, and how much I saved with the CCU.
This IAE I added an additional column for the chain number (so I can keep track on what CCU belongs to which chain. I naturally sort by this column and the from price every time I add something, keeps it nice and organized.) as well as a missing value column (when the 'to ship' price column does not match the 'from ship' price column on the next row, I use this to spot missing CCUs and potential for warbond CCU targets). And finally a sum for each CCU chain that calculates together everything from the 'actually paid' column and the missing value column to give me the current value of that ship.
Ah, after this IAE, the 'missing value' column is all 0s btw. Beautifully complete CCU chains, they're secure but not applied so I can still try to knock those two $200+ ships down a bit.