It's been bursting all year, and probably, realistically, since last year. Dealers just aren't selling cars, new or used, not in the volumes that they used to do anyway.
I guess all the financial and global factors previously mentioned are playing a big part, but more interestingly I think, is the age thing. The people who do aspire to a mid life crisis sports car, and can afford one, probably want something from their youth that the couldn't afford then or, something completely new and modern. A trad (or CX) Morgan perhaps doesn't fit the bill.
Morgan owners have for a long time seen their car as an 'investment' a safe place to put their pension money and enjoy it for a few years. No Morgan owner could ever see that the value of their car would decrease. I guess now, owners are still wanting 'top money' for their car even when there are a lot of cars on the market all competing for a very small pool of potential buyers.