I once wanted to calculate how much I have actually spent on steam. The information is only accessible once you log in. So, I wrote a tiny script in js that you can paste in your browser window to calculate that amount. Here it is:
https://github.com/dhawalhshah/steam-cost-calc
Steam gauge tells me the actual value of my games is $2019.05, but the amount I have spent is $432.75
Steam gauge tells me the actual value of my games is $2019.05, but the amount I have spent is $432.75