For my girlfriend's birthday I bought a spoiler for her Beetle from Spoiler Depot. Painted the total cost was ~$200.
The stock (bare) trunk lid and the spoiler. The spoiler was well packaged and the paint matched perfectly.
The inner hatch trip pops off without tools. It won't come completely loose due to the emergency latch for those people who get locked in the truck (?).
I'm doing this project by myself so I used a bungie cord to hold the hatch in a level position.
The installation kit comes with these marker strips to mark the holes. They stick to the spoiler.
I sat the spoiler in place and used a roll of painter's tape to keep it in position.
When the spoiler is properly positioned securely tape down the marker strips.
Then remove the spoiler leaving the marker strips. Follow the directions with regards to drilling. The inner holes end up being over the top of pre-existing holes in the trim. The outer holes require a little more work. You have to drill at an angle so the holes exit in the outer channel. Apply the gaskets, insert the screws, and tighten everything up.
I'd highly recommend a 5mm tool like this one for the install. It's long enough to reach up inside the channeling and allows you to easily tighten the screws.
The finished spoiler. I think it gives the Beetle a racy look.