Hi there Pinas,
For starters, I think of Rescator. Rescator allows you to search for credit cards via the last 4 digits of the card, perhaps combining that with a bank would allow for extremely accurate identification of possible matches.
For example: You could request the last 4 digits and institution of the card someone wants to protect or scan for. If the last 4 digits are '1111' and their institution is AMEX, and you find a '1111' and AMEX match on rescator, then you could view the full card details on rescator and request that the individual provide the CVV and expiry date - you use this to cross-match.
If they match again, you've got a 99.99% certainty of having found a compromised card of theirs, with the only risk of misuse falling solely onto you.
I'd be very interested to learn more about your platform, and when it's expected to be live/what it's capabilities are expected to be. Could you shoot me a private message some time perhaps going into a little more detail of what sites in particular you are searching through? I've got quite a large repository of underground blackmarket/stolen data trading sites that I'd be happy to share with you.
Let me know if you're interested, and good luck for the development of the system.
I hope this post has been useful.