I just found out that RadioShat has a number of battery holders. One holder interests me: RS 270-409. This holder completely encases and holds 4 AA size batteries and is pre-wired. For $2, it seems like a perfect match for my external battery pack requirement. I'm going to the local RadioSh*t to take a look at it and see if I can use it in place of the battery holder from an RC car I've been using. I'll post pictures later, if I get one.