leasing a horse would be better... you need to gain experience with what type of horses you actually like. Everyone here is telling you to buy a horse that will take care of you and won't try to kill you (aka an old, reliable horse) because thats the only type you can safely ride right now. If you gain experience you can buy a horse YOU like.
Also, is someone going with you to buy? Many people in this industry can be quite sneaky when selling horses, drugging or lying about them. You need to have an experienced horse person with you to buy. Do you know how to look for a drugged horse? Horse conformation? Health? You need a lot of experience with horses to correctly see these things if the buyer is lying to you. You also need to know the worth of horses in your area, so you don't get ripped off. Spending more time getting to know the people in the horse industry where you live would be beneficial. You could tell a trusted trainer or coach you are looking to buy, and they could help you.
Another good thing about leasing is the vet costs. You should experience the costs of owning a horse through lease first, so that you know you can afford it. Always plan for emergency vet visits, medication etc.
I think everyone on this forum has a passion for horses and understands how much you want a horse, but we also understand the realistic thing that it takes time to truly understand these wonderful animals. I just don't want you to make a mistake, which could be dangerous for you and the horse. I wish you the best of luck with whatever you decide. =]