I save both time and money commuting on my bike. Here is some of the breakdown of my big savings:
$ 300 per year savings by dropping health club membership
$ 125 per year savings by re-classiying my car to be driven less than 7500 miles per year and not to work
$1000 yearly savings from riding 3000 miles vs driving. The car costs about $.35 per mile to operate.
$ 560 yearly savins from not driving to the club twice weekly (16 miles each time * twice a week * 52 weeks * $.35 per mile)
That gives me a total of right about $2000

Expenses for my cycling last year:
$1500 New road bike
$ 250 SPD shoes, pedals for road bike and hybrid
$ 100 new winter tires
$ 75 new summer tires on hybrid
$ 200 misc parts chains, cassette, bottem bracket, cleaning supplies, and what ever else I've forgotten
$ 200 additional riding cloths for the Winter
My expenses this year: $2325

I nearly broke even this year and that incudes buying a $1500 bike!

This past year I was able to avoid having to do anything other than one oil change. As I am coming up to 100,000 miles, I am going to have to do some maintenance on the car this up coming year:
$375 brakes (rotors, pads) I'll do the labor myself
$ 25 Flush the brakes with high quality fluid
$100 Flush the transmission
$ 25 Air filter
$ 25 Cabin air filter
$ 25 Spark plugs
That will be about $525 in maintenance... if nothing unexpected need fixing. Cars are not cheap to keep of maintain, but I still need a car too often that we can't quite go down to 1 car. Even so, by cycling I am saving money i

For next year my bike costs will be a lot lower:
I expect to spend about $500 on a lighter/better venting Summer helmet, some additional shirts, and what ever other parts that I need/desire. So next year I'll actually start seeing major savings.

Happy riding,
André