Just think if you were going to have someone live in your home while you were away, wouldnt you like to have the added security that comes with the knowledge that the sitter/s have police clearance status.
Generally certification is valid for 12 months so one application could see you through a number of different sits.
In Australia, the cost varies from state to state so check the links below for a full listing of requirements and downloadable forms. You can also pick up the forms from a post office or police station.
Or use the National Crime Check site for a national service.
For the UK Disclosure Bureau (formerly CRB) check process, you can apply online via these links:
Online CRB Enquiry form
UK Disclosure Information Line Tel: 0044 8709 090 811
How to validate a genuine UK CRB check and certificat