Roland makes some of the very best Vocal harmonizers for sure in keyboards I personally loved the D5 & G70 models for sure among the best no doubt......Im sure Chas can enlighten you on the VP550 unit I think he owns one....may I ask why you think a professional unit like the VP550 overpriced? Vocal harmony is a art form in its own right and must be mastered very seriously in its uses or it will certainly sound inferior.