we found it to be well worth the expense to buy rechargeable batteries for all of our "gadgets". we have them for our radios, digital camera, gameboys, etc. We also have the quick charger that only takes an hour or two to charge, so we could charge them overnight. My DS's have had the same batteries in their gameboys for 2 1/2 years!
Even though it didn't work out for use (we may just not be buying the right brand LOL) I'm still a firm believer in using our DIS names when talking to each other w them....we use them in the mall....and all over the place here at home