Have students write thank you letters to faculty using free course materials. Create posters of these to post around campus.
Ask students to write notes to faculty/admin/state higher ed/etc. about their affordability struggles. Make a display physically or virtually of these. Invite faculty and admin to come and see what students are saying. Example of postcard to use. How this may look.
Social Media outreach
Create a hashtag or handle for your campus OER outreach. Keep it simple and uniform so that students have a regulated method to respond. Ontario example.