How much would it cost to upgrade my iphone 5s 32GB to the 64GB?

I just received a iphone 5s 32GB for christmas, but the home button isn't working properly (i have to click it a few times before the iphone turns. I think it might cost $200, can i do that during my new plan that was set up 6 days ago?

The storage can't be upgraded in an iPhone. You have to replace it if you want more.