if you got the money, go ori because aftermarket will not integrate nicely with the bumper. You have to cut holes into the bumper and the sensors may not match your bumper!!!
Going ori(parktronic) means you need the parktronic ECU, wiring harness, sensors. If you want for the fronts too, add another set of wiring harness and sensors. Each sensor will put you around RM400-500/each. You need 8 for ori front and back and you can order pre-painted (colour coded)
I am going aftermarket, camera instead. Won't look cacat too much. Plus, mine's alpine white...