I want a hamster really badly?

I have been wanting a hamster for over two years and i have told my mom numerous times, and she keeps promising to buy me one after i do this, or that, or that, but she never comes through with her promise. I am thirteen and i have written several papers on hamsters for school, gotten A's and shown my mom and she just says "yea ok nice". I would take care of it and i already chose a breed, a cage, all the feeding dishes, the straw, the food, and all accessories, and added up the prices and it was under $60 dollars. I am ready to care for it and i am aware that it smells and is awake at night, and i will have to feed it and clean it's cage, but i can't convince my mom. What do i do?