Duel Spec costs

Hello! I'm a new player here :)
I know that buying the duel spec from the site for the first time costs 100g. But is there any additional fee for swapping between the two specs? Or I can change back and forth as many times as I want?

And is there any fee for reset my spec? (primary/secondary)

Thanks! :)

After that first change its free to reset talents (via website) and swap between specs.