Joe, you might also consider a wall charger. I have the KabelDirect wall charger, which I bought from Amazon for $15.99.
I don't have an iphone, but this can be used to charge that, plus pretty much any other device. IOW, you can lend it (plus a cable) to friends with iphones, and you can use it yourself for your phone. I use mine to charge my cheapo tablet, my phone, my mp3 player, my portable battery packs, etc.
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