Thanks to everybody for their help.
We thought of the train/taxi to get away from the rigid tour bus times. But the train is $13.50 return, and the taxi is $21.50 each way, so there is very little difference to paying $36 on the tour bus.
Plus the taxi is a bit of hassle, you would need to book them, or so I was advised by Foxfield taxi company.
I thought that I'd be bored (as a man) after a hour or so, that's why I looked into other options.
But I'll have to just put up with it.