Wow, I don't know why Sam's said they don't have them. They are part number S59461B and the
web site shows that they have 101 in stock. Interesting however that they have them listed in the "port light" section rather than under "screens".

I just purchased some replacement "Fuller" portlights last weekand got a couple of screen at the same time.

Try calling them back and give them the part number listed above.