Just chiming in with our experience for the current semester (DS is an oos National Merit freshman):
*Total course fees are about $3500 - this includes 4 engineering school credits, 4 fine arts credits, and 7 arts/sciences credits , plus one course-specific charge.
*This semester’s books tallied ~$450. He has made purchases from Chegg, ZyBooks, Quia Corp, Codelab, and the OU bookstore. I believe a good chunk of the cost is coming from subscription/online materials access for German and Computer Programming.