I started out with an extra dining room/kitchen chair. I made a foam cushion to sit on. Then eventually bought an office chair on sale at an office supply store, but didn't put on the arms as they would get in my way. Still used the foam cushion.
Then I found the Dynadisc back when they were not so expensive. It is the same thing that the Gypsy Quilter? sells. This replaced the foam cushion.
Then took a class on [sewing] machine quilting with Harriet Hargrave and the whole first part of that class was on ergonomics and she told us how she bought herself a Herman Miller aerilon chair. Well, I went to see one, and [1] it was expensive!, but [2] it didn't fit my body. Whew. I saw what the worker bees used in their cubicles at this special office furniture store. They all had Swopper's. I talked the salesman into letting me borrow one over the weekend. I loved it!!! When I returned it first thing Monday morning I told him I wanted one.
Well ... it wasn't too pricey way back then but it wasn't cheap. It has been well worth every cent I paid. It is height adjustible and the balance can be controlled. It keeps me in an ergonomically correct position while I sew.
ali