To your point John, the FP1 and FP2 are extremely common in Germany, Austria and Switzerland, and somewhat common in the Netherlands; looking on machineseeker and other international auction/listing sites shows that dealers in all of those countries list them with the kind of regularity that you see Elliot / Victoria / Adcock & Shipley machines here in the UK.
Given that I would think that if Russel is willing to import from the continent, at dealer prices, almost any Deckel accessory he wants could be sourced easily via a bit of research and some emails.
I would note Stefan seems to be buying machines on the basis of them being for his business (which might now be a primary income stream), so probably was able to justify the dealer premium as offsetting loss of revenue if the machine was a dud or in time taken to track down and DIY the purchase (as he has done in the past), which most hobbyists might find harder to do.