Highly recommend checking out Maco in union city. It’s an office supply store that I think mostly does bigger accounts but I went in on a whim and got great service as a walk in pre-Covid. It seems like a small mom and pop shop but they have a lot of inventory and the sales person was really helpful and more than happy to pull parts from other chairs to assemble the perfect ergonomic Frankenstein office chair for me. It’s not cheap but I wanted a good quality chair and left happy.