Peter is 100% accurate. Trulia is a bit misleading in this area. You might gently approach the owners directly however, please be aware that most do not want to sell immediately. They want to stay in their home. Some do find a way to get current on their debt. They may not appreciate your offer to buy, but then again....
You are much better served by relying on up-to-date information which an agent can provide and putting an offer on a house where owners are motivated to sell. There are many bank-owned, short-sale and just plain motivated sellers out there. I'd much rather find you one of those if you're looking for a great deal.
BTW, anyone who tells you they "do it all," whether it's mortgage or real estate, please be wary. I am a certified short sale and foreclosure specialist and I'll tell you right now, I don't do all the foreclosures in New Jersey. You cannot be in this business and not work with banks. Find a qualified agent to work with and that agent will refer you to a very experienced mortgage broker.
Wishing you the best,
Helene Jeanette, SFR, SRES, AHWD, MBA