A couple people at work have been talking, and now I wanna start biking. The problem is, I have NO idea where to start. My main goal is to lose some weight(I'm a bit of a bigger guy), and just to be active, which has been hard due to recent knee surgery. I've been told to look into Commuter bikes, but like I said, no idea what I'm looking at. Do you guys have any tips for a newbie who's interested in this, and perhaps some direction as to where to find a CHEAP bike that's going to last me a bit? As a reference, I'd LIKE to get away with a bike under 200 bucks, but again, no idea what's a good deal or what's just garbage being sold as gold.

Any help is greatly appreciated. Thanks!