I'd like to hang a hook-arm off my desk's chrome wire rail to hold my
headphones. I do not want rounded S-hooks or J-hooks. I need a hook with
a level surface to hang stuff. Is there a hook less than $10 that's
already made to fit such a rail? Is there hardware that would allow me
to rig an attachment to the rail myself? Thanks.

hook & rail example: https://i.imgur.com/BNZB54n.jpg