I think this answers your comment:
The only time actually estimating cost comes into play is when the risk change is small enough to be close to the noise level. For example, deciding whether to pay more for a safer car, because the improved collision survival odds increase your life expectancy by 1 day (I made up the number, not sure what the real value is).
Imagine you're playing Russian roulette. Case 1: a six-shooter contains four bullets, and you're asked how much you'll pay to remove one of them. Case 2: a six-shooter contains two bullets, and you're asked how much you'll pay to remove both of them. Steven Landsburg describes an argument by Richard Zeckhauser and Richard Jeffrey saying you should pay the same amount in both cases, provided that you don't have heirs and all your remaining money magically disappears when you die. What do you think?