I would have thought something from the Yamaha or Casio range of electronic keyboards would suit very well.

I have a Yamaha keyboard which I got some 15 years ago and which has a five octave full size keyboard, velocity sensitive keys and a MIDI interface. It was not the cheapest in the range but reasonably priced and in general something with a similar specification is now very much cheaper. The quality of the sounds is reasonable and most electronic keyboards at least have a decent piano sound if many of the others are a bit naff. The musical director of our recorder society has borrowed mine on a couple of occasions and found it quite satisfactory until she eventually bought her own.