Gamiss offers this Sound-Activated LED Light in Black or White for $9.15. Coupon code "APRILNEW20" drops it to $4.51. With free shipping, that's the lowest price we could find by $4. It features a built-in rechargeable battery.

Note: This item ships from China and may take two to five weeks to arrive. Uncheck "Add shipping insurance to your order" to avoid the $1.99 fee.