I actually started riding my bike after I took my car into the shop 3 times in 3 weeks. I'm now at the point where I would like to just sell my car straight out and have the one car for our family.
Budget is tight. I bought a Mercier Orion 2007 for $100 from a friend, and invested only about $50 into lights and a mirror. I bought warm clothes as a second hand clothing store, and I use my old snowboard helmet (it's warm). I just started riding 3 weeks ago, and I anticipate it will have paid for itself at least by February, if not sooner.
Plus, I've tried for years to jog consistently, but I just hate it. My bike, however, is something I look forward to riding every day.