I agree. Although perhaps not 'rare' in the true sense, it's not exactly common either. Back in my youth, in the late 1950's to 1960's, there were quite a number of ex-RAF Magisters on the civil register, along with the civilian version, the Hawk Trainer. By the mid 1980', this has dwindled, to maybe seeing two or three at the annual Popular Flying Association Rally, held then at Cranfield.
I don't know how many are currently airworthy, but it can't be more than a handful, if that, with a few in museums. It was an unsung, but very important aircraft in RAF history, being a primary trainer, along side the much more well-known Tiger Moth, with virtually every RAF pilot doing his initial training on this type, at least in the UK.
The 'Maggie' also played a part in what was almost one of the most audacious escapes, by Luftwaffe PoW's, shot down in the BoB, when two of them 'borrowed' a Magister from an airfield in Cumbria, intending to fly back to France, but turned back over the Wash when short of fuel, landing in Norfolk.
As a piece of aviation history, it has its place, and is valuable if only for its historic background, but as pointed out, it may be just the piece someone is looking for to fit to a restoration, although depending on condition, it might only be suitable for a static restoration.
Not as 'glamourous' as a Spitfire tail wheel assembly perhaps, but still worth having.