I do agree entirely about the cost issues around the instrument. The big issue for me is the whole debate on beginner vs "pro" instruments.
As a melodeon player, i'm well away that a £200 melodeon is likely to be unplayable, however a second hand £400 or £500 is likely to actually be quite reasonable, and many people never feel the need to move on to a £1500 (or more) Castagnari.
However, with the concertina, there does not appear to be any middle ground. Second hand I can find a cheap concertina for £100, a second hand Rochelle for around £200, but then nothing until I hit around £1000.
From my position this gives me a very tricky decision. Do I go with the cheap option, for my daughter to try out the instrument, knowing that the instrument would probably only be good for a years playing, and potentially lose money on the resale? Or do I try and find £1000 to tie up for an indefinite period in an instrument, knowing that I would be able to resell without losing money (assuming she was carefull with it!)
With the Melodeon, I could happily spend £400 and get an instrument I could resell, but would also be good enough for several years playing.
I guess it's what comes with the territory of less commercial instruments, but i'm not sure there's an easy answer!