Charging rechargable batteries with a USB stick? Talk about ineffective - I use a standard wall socket charger instead.
In any case, here's the deal - if you're playing on your system VERY often, you don't need to spend extra on low self-discharge rate batteries. If you often leave it unattended for periods longer than a week or two, you could probably benefit from low self-discharge rate batteries. Weigh the pro's and con's, compare prices and then make a decision. If you'll end up buying a battery pack instead, make sure that it's a branded battery pack, like the suggested Energizer one - never buy
"No Name" batteries - they will likely quickly lose their capacity and if they do, you will be disappointed with their performance.