Als463 is right that bids are never guaranteed and that no one should assume that they are getting a bid anywhere. From what I have personally seen, it's not easier to join a GLO through colonization. The national representatives are going to be looking for high-achieving students (good grades and involved on campus) and a good mix of personalities. If you're going to go through with it, you need to bring your A game.
If you recognize those things and think you would be happy at Gamma Phi Beta, then I think it would be worthwhile for you to try to pursue the colony recruitment. I wasn't a colony member, but some of my close friends were when I was an undergrad, and I saw how special that experience was for them. It's definitely hard work to form a new chapter from the ground up, but their experiences were rewarding in ways they didn't think of at the beginning of the process.
These might be some places to start reading:
http://sororitygirl101.com/2012/07/0...on-a-tutorial/
http://sororitygirl101.com/2012/07/0...is-it-for-you/
http://www.greekchat.com/gcforums/sh...d.php?t=118074