The spreadsheet does nothing more than add, subtract, multiply and divide the numbers you input. If you're saving more than it shows then you didn't input the correct cost somewhere. This is one of those garbage in garbage out situations.
This: You must be plugging in some pretty serious Numbers in that Fancy Calculator or you need to shop supplys better. Because if you just look at the top Chart on the most popular calibers, SAVINGS are apparent right of the shelf price.