Tin whistle (aka penny whistle or Irish whistle) is an easy and cheap instrument for beginners. If you are new to the instrument, you don't need to invest more than $15 to get started. There are many models around this amount, but I would recommend going with a Clarke Celtic Tin Whistle in D. This is what I have and it seems to be highly regarded by others. The whistle is under $15 online. It includes a fingering chart with several basic tunes.
Here is a video of someone playing Scarborough Fair on this whistle to give you an idea of what it sounds like:
Learn Tin Whistle
While tin whistle is a fairly easy instrument, it may be a bit daunting to learn without any guidance. If you are a new player and don't have access to a teacher, you may want to pick up a book such as The Clarke Tin Whistle to help you learn. This book includes step by step instruction on how to play, reading music, and even ornamentation. It includes a CD with audio of all music in the book.
Digital Music to Print Instantly
The Tin Whistle Music store features PDF editions of our music with standard notation, tin whistle tablature, and chord symbols. Available collections include:
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