I've had a So Heavenly Seating sewing chair for many years. Yes, it was pricey. They have many customizable features. The usual (arms, no arms, etc.) and lots of others - seat width, height of shaft, fabric, etc.
Having been the buyer for furniture (among other things) for a small city school district, I can tell you that the gas cylinder that allows adjusting the height of the chair is what fails most often, and fairly quickly on many chairs. Few will give you the maximum weight limit, and even among those, when it says 250 lbs as an example, it is still not meant to be 250 lbs for several hours per day.
Size of the seat and weight limits are customizable on the So Heavenly chairs. Mine is still as comfortable as it was when I got it, and looks as good. My machine and fabrics are expensive as well, and I do not want to have a chair that makes my back/shoulders/neck hurt when I'm sewing.