Last launch we saw, we had to pay admission to the Kennedy space center and then a $50 per person ticket for the launch on top of admission fee. You have to be there early and they bus you into viewing stands and then bus you back out after.
Try this http://www.launchphotography.com/Delta_4_Atlas_5_Falcon_9_Launch_Viewing.html
I'm pretty sure you can buy tickets when you get there. However, I'm not sure if you can watch the rocket launch there, because it's once you get inside and everything. Though, I'm sure you could stay near the space center.
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