Like most hobbies or whatever it can be as much as you want to spend.
I use to sew clothes for myself and three kids so I already had somethings and gradually bought other things I wanted and thought would get me better results. In fact I still buy what I think will get me better results. I replace worn out supplies as often as I think they need to be replaced.
The only hobby I have now is quilt making and I make 10 -18 per year. I bought my fabrics at scattered times. Again fabrics can cost whatever one wants to spend.