I arrived at about 6 p.m. and there were only a few people queuing at the ticket counter. I didn't have to spend much time queuing. A return ticket cost only RM10 (adult).
If you're going during school holiday or weekend or public holiday, I recommend that you buy the ticket online to avoid the long queue. It might even be worth it to pay extra for a fast lane ticket.
I was told that you could also take a four-wheel drive up the hill and that would cost RM160. If you're more adventurous, hiking would take about 30 minutes.
The weather was a bit cloudy, so the sunset wasn't as spectacular as I hoped, but the night view was still amazing.