Personally, I think assassination markets could be a net benefit (think of the bounties on someone like Kim Jong-Il), but then, I like them enough that I write stories about them so I'm biased: http://www.gwern.net/fiction/The%20Ones%20Who%20Walk%20Towar...
"think of the bounties on someone like Kim Jong-Il"
Did you ever think of the bounties on anyone inconvenient to governments or big businesses? The founders of The Pirate Bay, Julian Assange and Bradley Manning, BP whistleblowers, environmental activists and climate scientists – would society be better off with them all dead?
One Kim Jong-Il is worth all of Pirate Bay combined, and heck, throw in Assange & Manning as well (they've informed the public, helped out the historians a lot, and caused some irritation, but I see few concrete changes to stack up against hundreds of thousands of dead).
Pennies is a bit extreme. The risk in the enterprise is pretty high, expert assassins rare, and amatures likely to get caught.
While an expert assassin may take a job on a random Joe for on the order of a hundred dollars, an amateur with any sense will not, and therefor the price will be rather high.
And, even if assassinations of pedestrians becomes realistically common..On the order of car crash mortalities, its at least a cause of death that may make people consider how they act toward one another.
Personally, I think assassination markets could be a net benefit (think of the bounties on someone like Kim Jong-Il), but then, I like them enough that I write stories about them so I'm biased: http://www.gwern.net/fiction/The%20Ones%20Who%20Walk%20Towar...