We've been buying batteries from online sources for years but recently discovered that we are in a minority on the issue. Here is what we suggest: you always need batteries at the last minute, right? You receive a gift and it doesn't come with batteries, your remote dies, your Sony Discman starts to slow, the power goes out and your flashlight hasn't been used in years. This is the reason why Energizer, Duracell and others are in business- impulse buys. Buy a block of rechargeables right now! A list of great buys is after the clickity.
Single use batteries are just about the most wasteful product you can have on hand. They provide energy for a few hours and then they become high-density, high-toxicity, hard to get rid of poison. Who would buy these if they had a choice? It's moments like NOW that can make the difference in your impact on your own bottom line, as well as that of the planet. We recommend NiMH for their relative low toxicity and ease of recycling quotient. The nickel content is an issue, but is the main attraction for recyclers- it makes it worth their while. Nothing is perfect, but these are a great value and last super long. NiCD batteries are pretty toxic, but since you are using them for so long, you are doing much better than commercial, single use jobbies.
Lithium is the best in terms of toxicity and duty cycle, but they cost a lot more. Still much cheaper than regular batteries in the long run, though. There is also the small matter of lithium batteries exploding on occasion… we've never had it happen, if that means anything.
BTW- most rechargeables are rated at 1.2 volts while their evil, single use twins are listed at 1.5 volts. Don't worry about this unless your product says that it doesn't work with 1.2 volts. Usually, you are not running at full voltage, anyway.
Here is a short list of battery suppliers that offer options that will save you huge amounts of cash in the long run (sometimes in the short, as well), and will give you hundreds of cycles. Think about that- HUNDREDS! Even if your rechargeables cost a little more, which they barely do these days, you will be practically making money on these! Yeah, you should take that literally.
The sites above also offer charging units to charge said batteries… just make sure you buy a charger that is compatible with your type of battery- most will tell you straight out "For NiMH batteries" or "For Litium Ion batteries"; you don't have to know about chemistry to match up the names.
Remember, it takes about a week just to get them so DO IT NOW!!! ;)