They are in $10. These are much larger than the ones at the resorts.
There are quite a few beverage stations around the park. The thing is there is a bar code on the mug and the beverage stations will not dispense if you do not have the correct code on the mug.
However, these mugs are good at both water parks. And any time you return you can purchase a currently valid bar code for a $5.00 and it will be good all that day.
And they are good for ordinary Coca Cola products, as sold everywhere at WDW.