I was at brookstone and saw a back up battery ipod charger that uses four double a batteries and saw that it had two price tags on it. One said it was 15dollars and the other said it was 40 dollars. i asked which the right one was and the employee told me it was fifteen. i bought it then when i got home and looked it up every website i find it on is saying it's 40-75 dollars. i was either really lucky, or they were having a sale, which i dont think they were because she didnt say anything about one. either way, pretty cool.