There was a topic some time ago regarding adapted or powered office chairs for the disabled.
In particular about the difficulties of obtaining one given that they are so expensive (c £4000).
It may be worth knowing that the Emove office chairs from Advanced Seating Design come up on Ebay from time to time, and tend to sell at quite low prices (£50-£400), probably because they are such specialist items so there are not many bidders.
Apologies for starting another topic, but the original was locked.