Walmart offers the Duck Brand Foam Socket Sealers 24-Pack for $2.88. Opt for in-store pickup to dodge the $5.99 shipping fee. (With orders of $25 or more, Amazon charges the same with free shipping.) That's tied with our mention from last week the lowest price we could find by $2. They create insulated seals for your interior and exterior outlets and switch plates to eliminate drafts and save on energy bills.