Why did the lease not work because you were sick? Could you not get out to ride him, or what? These are things you have to think about when considering buying your own horse. Who will feed your horse if you are unable to be there, become sick, etc.? Will your parents or a friend be willing to do it for you? Also, would the trainer at your lesson barn be able to help if you had a question about your horse's care? Or a horsey (adult) friend? You have to have ample resources and knowledge to responsibly care for a horse.