Tina entered the real estate business by an unusual route. She was a young woman trying to purchase a home with her husband-to-be. But the agent she chose was less than helpful, and Tina found herself doing much of the work herself.

After several frustrating months and more than a dozen rejected offers, Tina decided to take things into her own hands. She found a home she liked online and called the agent directly. "What is it going to take for me...