If an item of price $x$ is stolen from me or lost (assume that it is never going to be found again or returned to me), and I replace it by buying it again, but at its current price $y$, what is my actual loss? Is it $x$, $y$ or $y-x$?
Note:
This question stems from a real life experience where my train tickets were stolen from me and I had to repurchase the same ones at a higher price.
After the theft and replacement, you still have the exact same items you had before (assuming as in the example that the replacement is strictly like-for-like), but you have $y$ less money. Thus your loss is $y$.