[dkokelley]

I use the word "presume" because I don't frequent black hat markets and I have no personal experience with current pricing. The general agreement I'm seeing in the comments (and anecdotes gathered elsewhere) is that exploits and vulnerabilities command a higher price when sold to black hats rather than responsibly disclosed through a bounty system. (Isn't this what the grandparent and article are implying?)

This makes sense economically to me. In order for it to be worthwhile for a vulnerability discoverer to sell the exploit, the reward should overcome the cost. In this case, the cost is the probability of getting caught multiplied by the severity of the punishment.