If you live near a Costco you can get socks and underwear relatively cheap. I think the last time I bought a six pack of boxer briefs it was like 10-12 bucks
It was two packs of Hanes and UA socks that were on clearance. I had sticker shock at the total, but it guess it works out to around $20ish per pack which is about on par with my expectations. My kid is 16, and if I didn't intervene, he'd shove his foot into moldy old socks from when he was 10 and never complain. So I try to get him to go clean out his drawers as part of our back to school shopping.