Why do you need to contact the listing agents for these properties? You can work with any Realtor to see all homes that are listed in the local Multiple Listing Service, and to write an offer to purchase. As you have now seen, by using resources such as Trulia.com and many other web sites, you are not getting complete and up-to-date information that any Realtor can provide to you instantly.
As David has already mentioned, the listing agents may have a contractual obligation to represent the seller. You should find an agent who represents you as a buyer, or who works as a transaction broker.
These homes are under contract, and chances are very good that the sales will close. With the help of a good Realtor, you should focus your attention on properties that are currently listed. Your Realtor will also be able to immediately provide you with new listings within minutes of when they are listed, so that you will not miss any opportunities.
COLDWELL BANKER RESIENTIAL REAL ESTATE
423 St. Armands Circle
Sarasota, FL 34236