A4C offers the Duracell Powermat 24-Hour Battery System for iPhone 4 and 4S in White, model no. CSA4W1, or Black, model no. CSA4B1, for $19.95 with free shipping. That's the lowest total price we could find by $5, although it was $2 less a month ago. This charging hub includes a mat and case to wirelessly charge your iPhone.