Most other fields of endeavor aren’t compensated based on the black market value of the thing that’s being produced.
If we apply your analysis to other things, we’ll find that the upper bound price for a new car stereo or bike is ~ $100, and the price of any copyrighted good is bounded by the cost of transferring it over the network.
I think it is more useful to divide the amount Google paid by the number of hours spent on this and any unsuccessful exploit attempts since the last bounty was paid.
I’d guess that the vast majority of people in this space are making less than US minimum wage for their efforts, with a six figure per year opportunity cost.
That tells you exactly how much Google values the security and preserving the privacy of its end users. The number is significantly lower than what they pay other engineers orders of magnitude more to steal personal information from the same group of people.