I have a ballpark amount I spend annually and DH has a rough estimate on his hobby. When I first started, I was shocked at the cost. But now that I have a stash and try to buy only in completing a project. Thread, interfacing, fleece and batting are items I have to have. I do keep receipts in a file in sewing room and about every six months I go through them to see what I have used up and sometimes I see things I forgot about- without having to get out boxes or bins.