You should be able to find this on eBay.
A quick earch found five or so, ranging from $240 to close to $400
Authentic classics sells them. They sell the pieces needed (the insignia, the plate, the mounting clips and the mounting clips for the insignia) separately - which totals to $343
I would suspect other of the usual vendors might have them.
Note, the insignia for the delete plate is smaller than the one used on the trunk lid.