A while back I started a thread about eliminating feedback while playing acoustic guitars through a microphone. My sister is a performer who switches between three acoustic guitars, she does a lot of blues in her shows and plays some bottleneck slide pieces. She also plays a lot of finger picking and flat picking pieces.

Does anyone know of pick up device that she will be able to alternate between these guitars? It would have to be easy to change the device between songs. She would like to retain the acoustic sound of these guitars, not create a pseudo/electric sound. She has a relatively limited budget, $100-150 U.S. Are our we asking for too much?