Just buy your tickets on Traveloka! The 5,000 won't hurt, just pay for parking, hehehehehe...
Don't forget to take the train ride if you're here! You can tour three-quarters of the floating market area with beautiful views. There are also ducks, pirates, and water cars to explore the lake.
Don't forget to come early so you can enjoy all the attractions in peace without being jostled by other visitors. Good luck!