This is a loaded question, because it's such a polarizing question. The answer, yes or no, depends on the person answering the question. For example, yes, I believe that Sarah went too far at the end of the story; however, if you were to ask my wife the exact same question, she would most definitely say "no, Sarah did not go too far."
I think she went too far. She went behind her husband's back to move everything into the new barn he was building. She did it without his knowledge. She did it without consulting him. She did it while he was away on business for a few days. I will admit that Sarah expressed her desire for a new home to her husband. To her credit as well, her husband married her with the intention of building a larger house on the property. To her credit, she has waited through 40 years of marriage for the house. To her credit, her husband didn't consult her about whether to build the new barn or not. I believe that she has the right to feel slighted out of her house. Finally, to her credit, her bold risk paid off. Her husband finally understood how much the new house meant to her. I just don't agree with her method of going behind her husband's back.
Sarah has to understand that Adoniram's primary responsibility to her and the family is to love them and provide for them. He has done that for forty years. They have a roof over their heads. They own land and livestock. A new, larger barn will allow more income for the family. It's not like Adoniram went out and bought a fancy new racehorse just to look at. His actions will further secure the welfare of his family. Sarah has to know this. So to go behind his back and prevent him from doing that seems devious. Like I said though, my wife would disagree. Sarah did confront her husband about the barn/house issue, but Adoniram avoided the subject. I feel that Sarah should have found a way to make him listen to her reasoning. She didn't do that. Her actions forced him to see how strong her desire was, not her reasons.