Eventide makes few different rack models , I think they're all over the $2000 range ... Perhaps you may find one of these used for less than $1000 .
I recall that one of their products (I think it was "Orville" or "Eclipse") was about $4000 .

Don't think of getting one if you're not seriously into harmonizing , or you have some money to waste.


BTW , John Petrucci has got almost all of their product !