These are the companies who probably first search for cards.com and since it was already gone they got alternate names. Since you own "better" domain, chances are they would want that. The key is that your domain should be better than the buyer you are contacting.
Once you have generated a list of potential buyers from above technique, contact them individually ( NOT MASS EMAIL as it may be considered as SPAM ). Then follow TIP 5: Contacting Private parties and corporates.
Remember you are into Sales you should be willing to accept NOs, No replies, criticism, its all part of game. Make sure your techniques are ethical and legal. If you are asking $10000 for a domain, you can recieve a counter offer of $10, there is no need to feel bad or offended, it just means that you did not explain the value of your domain to buyer.
Once you have contacted all the buyers from above list and have not recieved any response, move on to next domain.