Firstly, given this STW, home of all things niche, the wider world isn’t as keen on rigid, single speed bikes as those here. It’s a limited market.
Secondly, anyone doing a search on say gumtree, ebay, isn’t going to think Curtis, unless they’re already fans of the brand. For a no gear rigid bike, £1k is a ot of dosh for s/h.
As an example, I could buy a new xt transmission from Merlin, new wheels from say Hinde, and a decent finishing kit, and have £500 left over for say a ti on one 456, new, for only £200 notes more. Its apples and oranges, but mainstream doesn’t want ss, rigid.
The person who like s Curtis frames and appreciates ss and rigid at a high price will like the bike, but you may have to wait, or split. Most ss users have it as a second bike, and £1k for a second bike in a recession is still a lot.