Hi naomi,
I do a fair bit of fund raising for my Rotary group - it may be worth contacting a local am dram group, as they may put one on very cheaply.
WE had one recently that was really good - and raised a decent amount of money.
When ever I mention the fact that it is for charity, most people / groups seem to bend over backwards to help.
As an example, we will be putting on a CSI night soon. Normal cost would be �25 - 35 per person. They are charging us �6 so that we can make money for the charity.
I would just say that 60 is a lot of people - we normally aim for around 40.