How useful is a larynx model in the voice studio?
If your student is a visual or kinesthetic learner, I would say that the value is immense. This model, 3B Scientific G22 2 Piece Larynx model, priced at $90 currently on amazon, is a wonderful addition to your "science" studio.
It clearly shows the hyoid bone, thyroid cartilage, cricoid cartilage, cricothyroid joint, arytenoid cartilages, and splits apart to show the true and false vocal folds. The thyroid gland is also on this model, although I tend not to discuss it much in lessons. I find it very helpful for some students to be able to see and touch a model of their larynx so that when I discuss basic vocal pedagogy, they have a clearer picture in their heads of what I am talking about. I find this visual feedback can also aid in heightening their proprioception (their ability to feel their larynx in their throat and perceive its movement).
Does everyone need this model? Absolutely not. If, however, you are a student of a scientific mind or a teacher that enjoy anatomy, this larynx is inexpensive, well-made and detailed.