I recently read that as the founder of the Talent Education Movement, Suzuki did believe that a parent should always buy the best instrument that he can possibly afford, with the belief that a quality instrument impacts a student’s enjoyment of his musical study.
At his piano lesson, the student is taught to listen carefully to his music and play with a beautiful sound. This is much of what makes it a rewarding and highly valued life experience. If he goes home, and the instrument makes it difficult to achieve these goals, he can become frustrated and discouraged in his practice, and at future lessons.
But it is a dilemma as some parents feel that since pianos are expensive, they do not want to invest in a better quality instrument. Since they don’t know if their student will continue in the long run with piano study, it seems logical to get an older, used piano that won’t cost too much. Then, they can decide if the student’s interest is strong and upgrade to a better piano.
Remember that unpleasant sounds detract from motivation and development. It is less satisfying if hours of practice can’t produce the desired sounds. For example, inexpensive electronic keyboards can limit control of dynamics and legato sound. Or, if deficiencies in the physical action of the keys make it extra work to achieve the desired results, that can also feel frustrating.