Instead of guessing, or spending tons of time trying to add up a total for/on trades. Could you implement a counter? Each time you select an item for trade it shows on the side or so how much your total is before you continue the trade.
That would be really nice. I am very happy with the total trade calculator but I still have to spam someone unrelated with trades to get the numbers right
Support - but maybe a counter that shows the break down for off/def of both spy and att items. And so that the person receiving can see too