Elements/batteries for motorized slider

I am an enthusiastic photographer/videographer, and i'm setting out to make a timelapse-slider. I have some experience with arduino.
The slider needs to slide a 5d with a lens (all together about 3pounds). The idea is to set it up with a potentiometer, so the speed becomes variable. I expect to build it, using the following components:

Stepper motor
Stepper Motor - 125 oz.in (200 steps/rev) (90N.cm)

Stepper Motor Driver
EasyDriver Stepper Motor Driver V4

Arduino Pro Mini 328 - 5V/16MHz (I will probably need the "FTDI Basic Breakout - 3.3V" to upload the code) Alternatively I am considering just buying an
Arduino Uno R3, as this is just as cheap...?

Some random potentiometer

I am a little confuset about the power supply (or supplies) as it needs to be transportable, batteries. I need at least 7V for the stepper motor, and 5 / 3.3V for the driver and arduino mini. Does anybody have any ideas regarding this matter?

Any help is much appreciated, Thank you!