You should follow the link on tba02 post. The calculator will tell you the wire gauge per amperage and for how many feet for the numbers you enter. Also voltages make a huge difference comparing 12 volts DC to 120v AC.
High amperage like 100 amps can be carried on 4 gauge wire but after a certain length , you need to step up to the next larger wire guage and so on.
Like Robb said, you can find the wire necessary at car stereo shops even big name auto parts stores sell some. Most sell them in a kit with high current bubble glass fuses and other useful hookup accessories.