Thanks, MacBoero.
Get a cheap drinks fridge, and modify the existing thermostat
Nice idea, and it has the element of a bit of a project about it, but the wine cooler is cheaper than any small (as in smaller than a domestic under-the-counter) fridge I have yet found.
It sounds like you enjoy making things work through computers. So how about these?:
I looked at items like these when I first set out to install the NAS in the garage, but the problem is that it runs Busybox Linux and is not a PC running a flavour of Windows. Additionally, it "receives" USB connections rather than hosts them. All this means is that I was not convinced that I would get them to work, so instead focused on finding a way to do the hack that I described in my first post. This was done with complete success (and not a little self-satisfaction of a neat trick well done, if I am honest)