I haven't bought a battery in four years.
More accurately, I haven't thrown away a battery in four years. That's because around that time I switched to only using rechargeable batteries for anything that took AA, AAA, C, or D batteries.
I remember my family trying to use rechargeable batteries in the 90's. I also remember that there was a decent amount of confusion about which chargers would work with which batteries. I also recall that those batteries lasted very short amounts of time between charges, were very expensive, and had a limited lifespan in general.
Fortunately, rechargeable batteries have come a long way since that time. Several years ago, I decided to try the most popular rechargeables, the Eneloop line from Sanyo (now made by Panasonic). This is a line of AA and AAA batteries that stores their charge very well when not in use, can be recharged a claimed 2000+ times, and work with most chargers.
I have a battery storage center in my laundry room where I keep dozens of rechargeable batteries, ready to go at any time (I need to get some more AA's as you can see). This is my workflow: when I remove a battery from something in my home, I put them right into my charger. Once charged, they go back in the battery holder, ready to go when I need one. I always pick from the first ones in line, and return charged batteries to the end, so I can cycle through my batteries evenly. The time to recharge isn't super quick - usually about 4-8 hours - but that's not bad if you have some extras on hand.
So far, I've found that my Eneloops offer up about the same battery life as a traditional alkaline battery. The life might be a little shorter, but that doesn't bother me when I don't have to run out to the store to get more, or keep 50 alkaline batteries on hand to make sure I have enough at all times and not making repeated trips to the store. I don't have to scour for deals on batteries, either, which brings us to the cost. This pack of eight Eneloop batteries costs $21.28 at the time of writing this. That comes out to $2.66 per battery. This pack of 48 Amazon-branded alkaline batteries (the cheapest I could find in a quick search) comes out to $0.25/battery. That's pretty cheap, and makes the Eneloops look quite expensive. But if you use one Eneloop more than 10 times, you come out ahead. Even if you take their claim of 2100 recharge cycles with a huge grain of salt and assume it's more like 700 cycles. Even if you factor in a shorter life on one charge than an alkaline would have (lets say 70%). You still come out way ahead (I've done the math at the end of this, if you're interested.
Eneloop used to make rechargeable C and D batteries, but they've decided to simplify their line and focus on the AA and AAA sizes. Instead, they now make plastic sleeves that act as spacers for C and D sizes. These sleeves accept a AA battery, and will power the device just like there were a real C or D battery inside. I was surprised to actually see this work, but the major downside is that a AA battery just doesn't have the same amount of charge as a C or D, so while it'll work, you'll find yourself changing and charging these batteries pretty often. When our son was an infant, I used these batteries in a swing we had. It worked, but I ended up replacing them every other day, so we ended up plugging it into the wall. If you're interested in C or D batteries, the EBL brand gets good reviews on their batteries and chargers. They even have 9v batteries!
I can't recommend rechargeable batteries highly enough. In the end, most brands these days will be fairly similar. I recommend Eneloop because they've been so good for so long, and still have some technological advantages over the others. They all, however, have significant environmental advantages over regular alkalines.
Lets do some math! I'll use my extraordinarily conservative numbers from earlier to make my calculations. I said that an Eneloop AA only had 700 charges instead of 2100, and could only power a device for 70% of the time that a 25 cent alkaline battery could. That means that 700 charges of the Eneloops had the same total supply of power as 490 alkalines. That still means You'll need to spend $122.50 on alkaline batteries compared to the $2.66 cost of one AA Eneloop. Rechargeable batteries do, however, have electricity usage costs associated with them, but those are surprisingly minimal - often in the realm of a couple dollars a year for all the rechargeable batteries in your home! The conclusion is simple: the more alkaline batteries you go through in a year, the more financial sense rechargeables make. Plus, just think about how massive a bag of 490 alkaline batteries is, and picture those in a dump somewhere. Then think about a single AA rechargeable battery. When that finally gets disposed of, it's going to take up significantly less space.