Sarah wanted an antique lamp for her bedroom. While in a second-hand shop, she saw a lamp that she really wanted marked $100. She offered the owner $75 for it. He said "I'll take $95." She answered "$80!" He said, "Lady, you're pushing me a bit, aren't you? I'll take $90, that's it." She said "OK I'll pay $90 if you throw in this old 'Vote-for-Pearson' button." He said, "Forget it, lady, my shop is closed," and asked her to leave. She said, "OK, I accept your offer of $95." He made no response. If she sues for breach of contract, which of the following is true?