Kate owns a shop that specialises in selling jewellery. On Tuesday, DeDe enters the shop and shows considerable interest in a watch on display in the shop. He wants to purchase it as a present for his mum's birthday. DeDe tells Kate that he is interested in buying the watch and asks the price. Kate says that she is asking 3,500 for the watch. DeDe replied that he would be in a position to offer 2,500. Kate says that 2,500 would be too low, but that she would definitely take 2,750 from him for the watch and says she will put the watch on one side until Saturday. The following day, Kate changes her mind about selling the watch, deciding to keep it as a present for her niece's birthday. Kate immediately sends a text message to DeDe explaining that the watch is no longer for sale. DeDe, who had decided that he wished to purchase the watch for 2,750, and despite receiving the text message, immediately goes to Kate's shop with the money and claims the right to purchase the watch.

Question - With reference to relevant cases, whether a contract has been formed between Kate and DeDe for the purchase of the watch.