I would do a google search for plumbing suppliers in your area.
If your looking for one of those grates that are around eight inches square with perhaps round pattern of holes. Any real good plumbing supply like Steve said should be able to help you out.
Can you take a photo of this so we can give you some more suggestions? Once we know exactly what you are looking for our advice may be improved as well.
thank you so very much .. You have helped me solve my problem. Good to go.