Yikes! They are all so expensive. Guess I'll be uncomfortable a while longer. :-( Thanks for all the replies.

I use office chairs at all of my machines. I like the way I can adjust angle of backs and the hight.

If you are able to go to yard sales - a lot of times chairs are available.

I was just in The Container Store yesterday. They have a chair that the back and seat are all bungee cords. It was really comfy! They have one with reg round bungees and a model with flat ones. I thought they were both equally comfortable and they come in COLORS! I think I will put the lime green one on my Christmas list!

I found a high quality leather office chair at an estate sale for $20. I am very comfy in it...great lumbar support!

I actually went on e-bay and bought a sewing chair with storage from the 50-60 era. It had new fabric on it and very reasonable. Love it, and it was fun finding just the right one.

I sit on one of those bungee chairs every time I get to The Container Store. We are moving to a place close to The Container Store and I feel sure that I will get one. Right now my sewing is on hold but I've been using a round stool from IKEA which has worked well.

I wish the bungee chair people made mattresses. :(

You don't specify exactly how you're uncomfortable. If you can't find an office-type chair that works for you, maybe try alternatives.
The ball chair someone mentioned earlier is affordable (I found them listed online in the $65 price range).
Another one that I haven't seen mentioned yet is the saddle chair. https://en.wikipedia.org/wiki/Saddle_chair
I have three quilting friends who each own a saddle chair, and they all love it. It's a bit more expensive, about the same price as a good office chair, but they all say it's well worth the price.

Good luck in your search.

I love my Koala chair. It adjusts from very low to draft height, which is great, since I'm short. It allows me to be comfortable at cabinets that would be too tall for me otherwise.

I have an Ergonomic Advantage chair for my DM and am considering a saddle chair for my LA.