Walmart offers the Essentials by Isotoner Men's Microterry Slip-On Slippers in Brown (pictured), for $3.88. Opt for in-store pickup to avoid the $5.97 shipping fee. That's tied with our January mention as the lowest price we've seen. (It's also the best we could find for any such slippers by $19.) These machine-washable slippers are available in S only.