TippingPoint s Zero Day Initiative is rated by researchers as the most trustworthy and is the preferred buyer. ZDI fared the best on trustworthiness, scoring a 3.5 out of 5, barely edging out SecuriTeam, which rated 3.3. The vast majority of vulnerabilities, both client-side and server-side, are being sold for less than $5,000. Only a handful of the survey’s respondendents reported selling vulnerabilities for more than $10,000.
Source: https://threatpost.com/survey-shows-most-flaws-sold-5000-or-less-052010/73994/