The Group Purchase Smart Contract allows multiple participants to collaborate in buying a product at a dynamically decreasing price. As more participants join, the price per participant drops, but it will never go below a set minimum price. Once a specified number of participants is reached, the vendor can finalize the purchase and collect the total funds. Participants who overpaid due to the price reduction can claim a refund for the excess amount. This contract ensures fair participation and proper payment distribution in a decentralized group purchase system.