The agreement to not solicit students from another studio does not need to be put into writing. It is an ethical situation. The bond between a teacher and a student (who often studies with the same teacher for 10 years) is either a "sacred" one or one that is not a good fit. Having seen this bond develop in my colleagues and their students is a beautiful thing. I would never dream of trying to take away a student from them even though I would LOVE to teach that student. On the other hand, the teacher can sense if he/she is not the right fit for a student and will sometimes suggest that a new teacher is found. I would never give a "sale price" on lessons to lure in new students. Music lessons are priceless and to reduce their value to a "sale" item, cheapens the impact of music on our society.