It's expensive in the first year, because you're buying tools and supplies that will be used for years to come. The costs go down as the stash grows and you can make quilts from what you have on hand plus a few pieces to finish them out.
I personally don't track what I spend (well, I have it in Quicken as sewing supplies but I never look at the totals.) It's less than I spend on books every month, I'm pretty sure.