buying a steel case gesture years ago was a great decision for me personally.
The chair is made to be sat in 8hrs a day nearly everyday. Office chairs at stores just aren't built that way I find.
The way I see it... I spend the price for this chair now... Or spend the equivalent or more over the years on replacements as cheaper chairs deteriorate.
While we're on the subject of chairs...stop buying those plastic chair mats. Buy tempered glass chair surfaces. They're tougher than you think, buttery smooth and don't flex and crack like the plastic ones.
Cut out the middleman and get some rollerblade wheels for the chair with sleeve bearings. They go over short carpet and hardwood floor and don't cause any damage.
Every single office chair I buy for myself and my family is followed by an immediate purchase of rollerblade wheels for that chair. Standard office wheels suck, and replacing them is really easy. They glide so well.
How flexible is flexible? The room I game in has uneven floorboards. I'd be worried that a glass mat, tempered or otherwise, would immediately shatter on anything other than a perfectly flat surface.
That's the reason I didn't buy one and made my own. Get a thicker piece of plywood in the size you want, get a box of stick on tiles, and get some decent trim to hide the edges of the plywood and you're set.