Brisk walking with jogging 5 days a week with building muscle and eating a lot of antioxidants really works for meCan always find a used bike cheap on Kijiji, eBay, etc. It doesn't have to be new. I'd recommend either a hybrid (what I have) or a road bike.
Last summer, I was doing 25km on bike everyday. Was a great way of losing weight. Honestly, it doesn't even feel like work...it's more fun than anything.