Am involved with small charity which is considering employing part time fundraiser, at this stage on a salaried rather than commission basis.

Is there any advice out there on what would be a reasonable rate of return when assessing the impact someone is having. For instance if someone is costing the organisation 10k p.a. would it be reasonable to expect them to bring in 50k p.a? 100k p.a? Sources of income are likely to be local government, public sector and be around delivery of services