Cheap window covering for french doors?

Window film, or gauzy curtains on thin rods mounted at top and bottom may be an option.

21 Creative Ways to Dress Up Your Windows On a Budget | HuffPost

https://www.huffingtonpost.com/hometalk/21-creative-ways-to-dress_b_8079476.html

Sep 2, 2015 - If eyes are the windows to the soul, then think of window treatments as the hairstyle, the make-up, or the jewelry. Windows without treatments ...

This is super cheap but I thought it turned out ok. We were in a rental house and the french doors were on a room we were using as a bedroom. Since it was a rental, we didn't want to invest a lot of money. I used a roll of brown Kraft paper from Walmart, stencil from Hobby Lobby, white craft paint and white duct tape to attach to the door. Stayed in place perfectly and removed without a trace when it was time to move out. I think total cost was $10 and I can use the stencil again. If I remember correctly, I didn't have to trim the paper to fit the door, it was a perfect fit.

Gathered Sheers

Cellular Shades

Roman Shades

Window Blinds

https://www.pinterest.com/2sherrie/window-treatments-for-french-doors/?lp=true