You will have to be a bit more specific as to what TYPE of door curtains you are looking for in both your question and your searches. I just typed in "door curtains" using the search web box on the answers page, and the results I got varied from bead curtains to fabric curtains to air curtains (whatever the heck those are!)

I would suggest you google 'where can I buy door curtains'. I bet you will have dozens of choices to make.

Try a curtain shop.

check online or go to oJ.C. Pennays.

Anywhere that sells curtains should have curtains of that length.

Sears catalogue use to have them