I've tried contacting banks directly for an investor I work with, to no avail. They are just overwhelmed with properties, so don't know how to handle a request for purchase.
You might put together a good offer, find out the name of asset manager, and submit the written offer directly to the asset manager. Chances are slim, but making a direct approach with a healthy deposit might pull it off. Find a title company to hold deposit, or better yet, state in offer binder due one day after acceptance. Keep in mind the asset managers have no experience in selling a property, which is why they rely on getting it listed when the time is right.