Thanks for responding, Ilja!
I have tried a bunch of approaches, and the code below is only my most recent failure:
tell application "GarageSale"
repeat with theListing in (get selected ebay listings)
set theOption to (the shipping option of theListing)
set the originating postal code of theListing to "94702"
I have tried it with and without quotes around my zip code.
I went in with
shipping option business because that's what worked in a script for adding and removing domestic shipping services. This was after failing with a version based on a script for changing the design identifier that just used
If I run the above script from Script Editor with one listing selected in GarageSale, this is the error I get:
GarageSale got an error: Can’t set originating postal code of ebay listing id "2F7B662F-388C-47DE-8504-9ABEDF9ED7D7" to "94702".