You don't say what year you have but on the 2001 and newer there is no need to replace the filter unless you really want to. Some guys drain and refill there tranny fluid with every 3,000 mile oil change. Not a bad idea when you figure it only cost you labor and 4 quorts of fluid .The book say's 2 quorts but trust me, you will need 4.
If you want to change the filter it will cost you about $35.00 for the kit and that's the only way you can buy the pump. It includes the pump and the pan gasket and the drain plug gasket. Mike