Designer Living offers the Protech Alpine Twin Mattress Pad for $17.99 plus $5.95 for shipping. That's $52 off list, tied with our mention from last summer, and the lowest total price we've seen. It features 3M stain release protection.
Of note, it's available in California King for $28.79 plus $5.95 for shipping. That's $81 off list and the lowest total price we could find, although we saw it for $11 less last summer.