How expensive this hobby is is directly related to how much you can afford to spend on it. For me it's expensive because I live on a fixed income (SSDI) and have subsequently low disposable income. I have to plan every expense, which limits what I can afford to do. On the other side of things I know folks who wouldn't hesitate for an instant before dropping $20,000 or more on a new jet.

"Expensive" is far too relative a term for definitive declarations.