Out of the 3 Keyboards you mentioned (Korg PA80, Roland VA-3, or Casio MZ-2000), the casio MZ seems the "best for your buck I would say. the PA80 falls into that "mid-range" catagory.

The VA-3 is a toned down version of the other two (VA-5/7 - which I don't rate too highly anyway (personal opinion), with the PA80 being a Toned down version of the Korg triton engine. It's hard to say which sounds best in writing, but the Casio is really a super keyboard, and has an excellent Piano on it. Also the Casio has a superior DSP effects section compared to the other two. there is a KN5000 which is, in my opinion, better than all three, but you must listen to them yourself, and then decide.

Regards.

Tony, England, UK