Harbor BridgeClimb experience
I took the twilight Harbor Bridge Climb on my last trip to Sydney. Yes, it is expensive, but it is fantastic experience, fun and totally worth the cost, in my opinion.
As a matter of fact, I was the only "tourist" on my Climb. All the others were Australians, most from the Sydney vicinity. For some it was because of a birthday or some other life event. Everyone had a blast, the guide was superb, very personable and the entire experience was exceptionally professional.
I would do it again on another trip to Sydney.
The views from the top of the bridge at dusk were spectacular, and then we finished the Climb at night with the city lights twinkling all around.
^