Rob,
1. The PCC (personal charging case): charge one battery (and carry an atty and two carts), while you're
vaping the other. Cost: $20-$35.
2. USB Passthrough: for use when you are at the computer; save your charged
batteries for when you are out and about. Cost: $15-$25 or $50-$75 (for the deluxe, high-powered ones).
3.
MEGA batteries: 280 mAh, rather than 150 mAh. [NOTE: Will fit in wall or USB charger, but not in PCC.] Cost: $20.
4. The ultimate solution that most vapers turn to sooner or later: The Mods (360 mAh to 3000 mAh) ... or the new 650 mAh eGO aka Tornado (which is not really a mod). Cost: $50 - $150+.