In the school supply section of my local WalMart, they have some "pencil cases" in different sizes. Soft cases that run about 4 dollars that have a zippered upper and lower section so you can place a MOD, 2 Ego type devices and lots of juices and a charger/batteries.
In the same section, they have hard cases with a lock from Vaultz. These are nice too and have sections inside that are elastic that can hold batteries and tanks.
This is in the front of the store, not where the pens and pencils are. They have the seasonal stuff or the back to school stuff in the front of the store. LOL just seeing all the pens and pencils makes me want to go back to elementary school.
The Vaultz cases are almost like this one, they are 9.99 and don't have the handle.
They measure about 9 inches long, 10 inches wide and about 3 inches deep.
http://www.walmart.com/ip/Vaultz-Protective-Medicine-Case-1-Pk/13864190