For its newsletter subscribers only, newegg offers the Energizer Rechargeable Portable Power Supply Kit, model no. XP2000K, for $19.99. Coupon code "EMCYTZT3439" drops it to $16.99. With free shipping, that's the lowest total price we could find by $35. It features six cell phone tips (including an Apple 30-pin) and provides up to 12 hours of extra power for cellphones and up to four hours of extra power for smartphones. Deal ends May 16.