Of course, think rechargeable.
Not only are these more environment-friendly, they are really actually cheaper in the long run. And you don't really want to keep shouldering the manufacturing costs of disposable batteries, now do you?
Now, say you just bought this new, expensive gadget. Be it a mobile phone or a camera, one other investment you can complement the purchase with is buying extra rechargeable batteries.
Because not only does it save on costs for you, but it also prolongs the battery life of your gadget's original batteries. Plus, it saves you the hassle of always having to charge your one battery pack even if it's not yet fully drained out of fear of your gadget dying on you while you're out.
So get at least one other battery pack. If you're investing on rechargeables, you may also want to get one of those turbo chargers so you need not wait a long time before all batteries are charged.