I’ve been looking up this concertina on ebay (looks like the seller relisted it at $2399) and found this forum discussion as a result. Just wanted to weigh in.
Looks like the seller now has two positive recent feedback, and has revised the listing with all new original pictures, and now states that all the notes play and sound great and in tune, that there is no ciphering, and that the concertina bellows are tight and performs well under a “hang test”.
Also, I just took a look at the seller’s feedback from his old ebay username (antiquitymusic_com), and he received a positive feedback for an equally expensive Lachenal Edeophone back in January 2014.
Sure doesn’t seem like a scam to me...