regardless the volunteers from Bishan Club, SIXGA or other clubs, our practices to pay tokens of allowances (we paid between $25 to $60 per actual work day from the past 6 years records, no payment for the planning and preparation) as ways to show our appreciations to them, the differences could be we pay less to our members in general.
We should not expect free services from volunteers as they need to spend times, take leave etc.
Of course, there is no way for us to pay so call x times of "one-day salary" to them for taking leave to work with us for x days.