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I don't inventory to figure out how much money I spent but rather to see which components I'm low on and how long I can continue shooting at my current rate if I couldn't get anymore supplies.
I only reload 3 calibers so it's not that hard. I have a spreadsheet set up that does all the calculations. Completed rounds I weigh and plug in the weights to get the number of rounds. Primers are on separate shelves for SPP, SRP and LPP, those are counted to the closest hundred and input to the sheet. Full bottles of powder are counted and partial bottles weighed. When that info is input it gives me the number of rounds that can be loaded with each powder since I use a different powder for each caliber.
Another area takes the number of completed rounds plus the number of rounds that can be loaded using the lowest component level to give me total available rounds, and after I input how many rounds of each I shoot each week it tells me how long I can continue at that rate.
This whole process (now that I have the spreadsheet set up) takes me maybe 15-20 minutes and gives me useful information.
I do something similar with my spreadsheet.
I basically track my components and the cost of it. That let me calculates my cost per round, 50 rounds etc. This also means I know roughly how much I spent on all my reloads so far.