West Audio via Amazon offers the Duracell Powermat 24-Hour Battery System for iPhone 4 and 4S in Black, model no. CSA4B1, for $8.99. Plus, Prime members qualify for free shipping. (Non-members can spend $35 to qualify for free shipping; otherwise, it adds $7.15.) That's a buck below last week's mention of another color and the lowest total price we've seen. (It's a current low by $6.) This charging hub includes a mat and case to wirelessly charge your iPhone.