Steve G1KQH told me of a good, low cost, source of the crystal needed. This is in the USA, so I ordered some and these have now left Heathrow, London, so they must have been in stock and sent by air. I have no idea if I will have to pay VAT or duty. I hope not.
As my fine motor skills are poorer since my 2013 stroke, I want to build this in parts, probably starting with the RX. Assuming this is OK I shall have a go at the TX, then combine as a transceiver. Being largely based on the 10m WSPR WISPY it should work.
UPDATE 1220z: Crystals have arrived from the USA in the post just now. No duty or VAT to pay. Just need to build now! Excellent.