Target offers the Biddeford Heated Full Mattress Pad for $17.48 plus $7.20 for shipping. That's tied with our mention from three weeks ago and the lowest total price we could find by $22. It's made from polyester and features automatic shut-off and lighted control.
Of note, it's also available in Queen for $24.48 and King for $27.98, both with free shipping. (Queen size requires padding over $25 for free shipping.) Excluding padding, they're price lows by at least $33.