Get a wallwart for now.http://www.mpja.com/5-Volt-DC-Plug-Power-Supply-4A-Regulated/productinfo/18520%20PS/Replace with a 2-cell (7.4V) high amp-hour LiPo later on when you've determined your actual needs.
Google LiPo batteries, they are common & inexpensive, many radio control car places carry them.You said the motor and driver are both rated for >7.4V; no resistor needed.
So I need to hook the wallwart up to a 2A resistor to use it?
I need to find a battery that can give me 25 hours, or at least 12... that's also cheap... $25 is ideal. Anything over $50 I probably cannot consider.