The cost savings are immediate, but the benefits are beyond price.
I eat and do laundry, anyway. I have a large family so laundry is almost a continuous process. An extra couple of bike shorts don't generate additional loads of laundry. As for food, I probably eat more, but only a little more, and not enough to register. I do, however gain the satisfaction of being able to eat and not feel guilty about it.
Knick-knacks and cycling gear: This is controllable expense. You don't "need" to keep spending money on this stuff, but there are things early on that will improve the utility of your bike, or your own comfort. Some of these things will wear out and need replacing over time, but consider this. In the US, we are obsessed with vehicles and we spend a lot of money "improving" them. If I wasn't spending money on my commuter bike or my bike gear, I'd probably be spending it on my car.
Furthermore, bike stuff only seems expensive when you consider your bike to be a toy. When you treat it like transportation, it's a steal. I just changed the oil in our minivan the other day and spent over $60 in supplies before I hit the garage. And I still need to have someone flush and fill the radiator and replace the transmission fluid, and I need a specialist to inspect the brakes because I don't have a micrometer, nor any way to measure "runout" on the discs. And this is scheduled maintenance!
If I wasn't biking to work, I would need some other form of exercise. This could mean gym membership, or it could just mean additional road biking outside of commuting. Either of these would require more money and more of my time with no return benefit of transportation. If I didn't exercise, I could expect to visit the doctor more often and to experience more serious health concerns, or to eventually become dependent on full time health care at an earlier age. How much does that cost?
When I bike to work, I am a happier and more productive person. What dollar value do we assign to that?
This morning in the soft light of early dawn, I saw three deer run across the road ahead of me, leap over a fence, and take off across a freshly mown field of hay. It was beautiful. What price, that?