Yes, given the recent Facebook Timeline changes it makes sense to look at starting a group on Facebook. But, buyer beware - it's actually free - don't start a group until you've outlined your group strategy. Why? You're not just launching a group, you're building a community.
Group development is a skill. You don't just get to be the cheerleader who barks at your group to get engaged. You need to have a defined strategy of how to acquire new members, maintain engagement, and build community online and off-line.