Don't forget penny whistles or the tin whistles of Ireland. They are relatively cheap, around $7.50, and are easily made from rolled tin. They come in different keys, D, G, C, etc., but the most popular D. They have only 2 sharps, F and C. One has to learn how to transpose songs and how the breath works, etc. but it is easily carried in a pocket, unlike a piano.
Offered by Kristy.