PCB Track Width for High Current
What matters is your total copper cross section and the trace length. Both of these numbers contribute to the total resistance of the trace (if that's important) and the resistance per unit length which contributes to temperature rise (if that's important). If it's a DC current, there are no issues that I can see. For higher frequencies, you might be generating magnetic noise if your return trace is farther away. (Magnetic noise is proportional to current x current path loop area)

Here is a website that can help you calculate the total amount of copper based on the target temperature rise: http://circuitcalculator.com/wordpress/2006/01/31/pcb-trace-width-calculator/

Edit:
Another way to go on the cheap side is investigated by Dave Jones and Mike: 

EEVblog #317 - PCB Tinning Myth Busting (14 minutes youtube video)

Does putting solder on high current PCB tracks help? (4 minutes youtube video)

Basically, leave your trace open on the soldermask, then go over it with a LOT of solder to beef up the trace cross-section. Another possibility is to just use a big fat wire to jumper it across your PCB.