It's $8 to park at each of the 4 parks (MK, AK, MGM, and Epcot). You only have to pay once per day; display the parking pass in the windshield and if you park hop there will be no additional parking charge that day. There is no charge to park at the resorts (hotels), but if you are not a guest at the resort, there will likely be a time limit of 3 hours imposed (enough time to tour the resort and/or have a meal).