The kids and wife have bought Ikea chairs and gaming chairs on line, very rarely do they last very long, I bought one from PC world years ago and it still serves my needs at this PC, the workshop has a standard metal framed chair that neither lifts or rotates (sounds like a bra advert), it came with a metal bunk bed futon combination for one of the kids room, the wife has many a time asked for me to replace the computer chair and I refuse, it has garden chair and an Ikea cushion on it to relieve the posterior.
They purchased a really good leather chair at the wifes work after she bought it to help with her back after the Ikea ones were hurting her (and actually her work mates) i.e. they refunded her and then bought several more as they were really good, but no good as a workshop chair.
Baldrick, the thread bare nature of your chair is not a problem, just have made a beret style cover made to suit the seat out of a similar of more hard wearing material, with a thread edging line that found on jogging pants the cover can be made to stay on (rotating is not an issue) and washing/replacing it could be done without much effort.