Walmart offers the Duck Brand Vinyl Clad Door Seal in White for $6.92. (With orders of $25 or more, Amazon charges the same with free shipping, although it's currently on backorder.) Choose in-store pickup to avoid the $5.99 shipping fee. That's tied with our mention from last week, $3 off, and the lowest price we could find. It fits most doors and fills gaps to prevent unwanted dust, pollen, and insects.