That's $6 per battery. I picked up FOUR AAs with a recharger from Walmart for $10, that's $2 per battery and $2 for the charger. I charge my phone via USB too (I'm guessing you have a RAZR or SLVR) but I charge it everynight, how often are you going to charging batteries to make the USB ports more convenient than a wall outlet. I know my batteries take 17.5 hours to charge, I don't want batteries sticking out of my laptop for that long. I must admit though, it's a good idea when you're out of options, but I wouldn't use it as a primary solution simply because it doesn't offer anything other than a travelling gimmick. When you starting moving up to buying USB hubs to charge batteries, then it become even more trivial because it's the same as buying a recharger.