As someone once said, being a sellers agent is like having hundred agents working for you to get the buyer.
Most buyers have agents that they're working with and if their agent comes across a deal that they'll get 3%, they'll be sure to push their clients towards it.
Unless you're giving 5-6%, you won't get a sellers agent that will offer that much to a buyer's agent because it will take from their cut. That is why I posted that link, I know people who've successfully used that website.