Welcome to the forum.
I bought my cutter pan from pizzatools, at http://www.pizzatools.com/
. They cater mainly to the pizza trade and make very good products. I have several different pans/screens/disks from them and they are of very high quality. However, they are not cheap.
If you go to their website, you will see statements like "business to business sales only" and "no sales to the public". That doesn't mean they won't sell to you. I called them a while back for clarification on this point. The customer service person I spoke with said that anyone can order items from the pizzatools.com website. They will also answer questions about their products over the phone. What they cannot do is take orders over the telephone. I was told that they are not staffed to do this. I have always ordered online from pizzatools, so that hasn't been a problem for me.
You should, of course, check with local restaurant supply places to see if they carry the cutter pans.