I was planing on something like this for the Arduino power: http://www.beboxx.com/coen/arduino-9v-battery-cable.html?currency=USD&track=feedgCrS
There is a bit of a concern of keeping things small on the Arduino side of things as this is going to end up going inside a toy.
Also I think the 2AA battery step up wouldn't be additional hardware if I get this: 5V DC to DC Step Up - 2xAA - PRT-08249 - SparkFun Electronics
I'm trying to keep the accelerometer end of things light weight. I'll go ahead and get the 2AA battery pack as well as the 4AA battery pack and see which one works the best for the project.
I assume the 4AA pack that I would need is this one: Battery Holder - 4xAA to Barrel Jack Connector - PRT-09835 - SparkFun Electronics
So just to summarize, I'm planning on the 9V battery for the Arduino+XBee Receiver and then getting both the 2AA and the 4AA packs for the Xbee Transmitter and seeing which I want to go with. Does everything else look good? Any advice on how easy/difficult this will be to set up?
Thanks again