If you can afford, pay both. In order for it to work you have to play with different settings in you campaign to optimize your ROI. Word of advise, DO NOT leave your program on auto-pilot. That will result in loosing your positions and wasting a lot of cash. Personally when I set my new campaign I have to keep an eye on it for at least a week or two, checking it a few times a day, until everything settles and I establish my comfort zone.

__________________
Site for sale: http://reviewgolf.com

"Web design is the area saturated by amateurs that confuse software capabilities with their own talent." ~~ me