I think how much a hobby costs really depends on your dedication to it. Buying one necessary object and using it over an extensive period of time isn't really what most dedicated hobbyists do. I would assume cyclists are frequently checking out new helmets, clothes, tires and even whole new bikes all while maintaining the stuff they already have. It's like photography. Yeah, you can be a "photographer" with your $300 point and shoot or you can be really serious about it and buy $3000 cameras, spend hundreds on lenses and film, buy all sorts of editing software and pay for expensive printings and frames.