Shar Nicholles owns a 25-acre parcel of undeveloped land west of Salina, Kansas. For most of her life, Nicholles had been an astute and successful businesswoman, having made her fortune buying and selling oil and gas stock. By the time Nicholles was 85 years old, she had been diagnosed by Dr. Law as being "very senile and confused 90 percent of the time." One day, a shifty character, Greg Weissenguru, was riding his horse past Nicholles' property. Weissenguru decided he wanted to buy Nicholles' property. Later that evening, Weissenguru tracked down Nicholles at the Dimaru Asian restaurant, which everyone in town knew was Nicholles' favorite place to eat. Nicholles had no idea what the property was worth, so Weissenguru asked his friend Evans to appraise the land. Evans appraised the land for $50,000. Nicholles and Weissenguru agreed to enter into a contract for the sale of the 50-acre parcel for $50,000. Weissenguru agreed to pay $1,000 at the time of closing and $49,000 whenever he developed the land and sold it. There was no limit on Weissenguru's right to develop the land. The contract also did not include interest on the unpaid portion of money. Nicholles dies two weeks after the contract is finalized and signed. The estate now wishes to set aside the contract and cancel the sale.

Is this a valid contract? When answering this question, discuss whether the elements (offer, acceptance, consideration, legality) of a contract are present. Further discuss any argument the Nicholles estate may assert. Will the Nicholles estate be successful?