How much to rent a Sanpan in Sai Kung?

How much should we pay to have one of the sanpan ladies float us around the outlying islands near Sai Kung? Thanks.

I paid $300 for about 5 hours. Even got the brother of one sampan lady to come with us (she spoke no English, he was fluent) and he acted as a guide...didn't want paying, but of course he did. He is called William and is a retired airport baggage handler - just enjoys going out with foreigners and practising his English.(and obviously getting some worthwhile money) I have sadly lost his number which is a shame as my family thought he was the best. My five year old was even allowed to steer the boat! If you see a William let me know! He took us to a deserted salt mining island (name I can't quite remember at the moment and half moon bay). It was a lovely day out and the children want to find him again so that we can go fishing.