I had thought of KA relays, but even second hand the costs still mount up pretty quickly. A horseshoe console with less than a dozen stops is starting to look a little bare. Ideally I'd hope to grow to a couple of dozen stops, drawn from 4 unified & extended ranks, over 2 manuals and pedals. I also have something of an attraction to the engineering in the 1920s electromachanical and electropneumatic relays too. The combination of polished wood and brass can verge on art.
Thanks for the link to Classic Organs. Unfortunately, at £200 per rank plus extra for extended stops, this is out of my budget.