Droddey... been in Office Products for 40 years. There is a huge difference in the discount house chairs and a quality chair. HON is by far the leading chair maker with decades of experience. The ones that are good for you and would be considered an "all day" chair (as opposed to a 20 minute chair) is going to have ergonomic qualities.
The primary differences are going to come from:
Construction - Pick it up. A good quality chair is heavy. No if, and or buts.
Adjustments - Higher quality chairs have tons of adjustments to custom fit the posture to you. Lower quality basically go up and down and the back sometimes raises up and down.
Expense - While not always the case the better the chair... the more it cost. (***see below)
Fabric - The better the fabric the more it cost. Sometimes the same chair can be had in say an A,B or C fabric grade which affect the cost.
*** If you can go to a mom and pop office furniture store you can sometimes save money in these ways. A custom chair that was ordered and the fabric came in wrong. They are sometimes either stuck with it or it was comped to them so they have zero in it. Shipping chair mistakes back is not feasible. Also we order chairs in bulk for a local Air Force Base and also our College. We might have a customer order 90 chairs and maybe we get another level price break at 100 so we order 10 extra. Those 10 chairs are super high quality that we got a huge break on. We can pass that along to our customers. That's why I say try a mom and pop store and they can cover the chair adjustments with you. Makes a big difference. Might let you concentrate on your music instead of why your legs are going numb. The big box stores usually can't do anything more than telling you aisle 7.