The market for 0days has been cooling off in recent years, but for a good decade there you could sell 0days, even mediocre ones for six digits. Nowdays you'll need a pretty good vuln for six digits, and something pretty stellar for seven (this isn't unheard of). ZDI, frsirt and others got into the game as middlemen. They allow(ed) you to not know who the final purchaser is and would allow you to sell 0days that may or may not be interesting to a government entity - in this case ZDI, etc would swallow the cost.
The market for 0days has been cooling off in recent years, but for a good decade there you could sell 0days, even mediocre ones for six digits. Nowdays you'll need a pretty good vuln for six digits, and something pretty stellar for seven (this isn't unheard of). ZDI, frsirt and others got into the game as middlemen. They allow(ed) you to not know who the final purchaser is and would allow you to sell 0days that may or may not be interesting to a government entity - in this case ZDI, etc would swallow the cost.
Edit: http://www.vupen.com/english/services/lea-index.php