There are plenty of groups that have tried to run a Chipmunk without realising it is not a cheap aeroplane to maintain. I don't know why that should be, as Chippy costs are well known - maybe there are a some dreamers out there who think it can be done cheaply?
You have to realise this is an English military aeroplane not designed for cheap maintenance, it is a classic for which some parts are becoming expensive (read:rare). Well run groups budget for all of this and buy up likely spares as and when they become available so they are 'in stock' for when needed.
I fixed that for you
There are lots of military trainers from eras before and after that don't have the same level of designed in maintenance requirements, and I think many of those "dreamers" own them, individually and without undue hassle. The Stearman is one that comes to mind, with its 220 Continental, or the various Cub-like L-birds with their flat engines. Even a Ryan PT22 with long obsolete Kinner radial is probably easier to own. British origin stuff very often incorporates fussy ownership issues as par for the course, while other stuff sought to eliminate the hassles.
I know the Chipmunk is really Canadian but the lump on the front and so many of its systems were dictated by the customer.
I remember once having an artillery engineer at Piccatiny Arsenal explain to me the differences between the Russian D-30 howitzer that he liked and was studying and the British designed M119 that he was tasked with developing for US forces. One difference he noted was that the British gun was designed to have a devoted mechanic on the crew!
I'd like to have a Chipmunk just because I think they're cool, but I think I'd like to have an 'engineer' (mechanic) on staff that wouldn't be necessary for some other comparable planes.