A while back ago i found an electronic capo that is just like a regular capo but can have certain strings open. For example you'd put the capo on the neck at the 5th fret. Touch the 1 3 and 6 strings on the 5th fret, and the rest would be open. I found this a long time ago and cannot remember what it is called. If anyone knows what i am talking about can you tell me the name of it.
I just checked sweetwater. Its not electronic but there is a planet waves spider capo that can do what your saying and its only 30 bucks how good is it I dont know
Sorry its made by "creative tunings" and Morpheus has a capo pedal that is supposed to do what your saying $200