I don't see why it's such an expensive 'hobby'.

I picked up an older Schwinn Prelude for a hair over $100, got a helmet, pump, spare tubes, a few tools, lock/chain, etc. for under another $100.

As with any other hobby, if you keep expenditures realistic to what you actually need, you can do a lot with just a little.

I'm in a similar boat. I quit smoking a little while back, am getting in shape, and bike commuting whenever I can. My main job is ~15 miles away over rolling foothills that absolutely destroy me... but I'm working my way up.