I agree, get the full size chanter because your fingers are going to be learning the spacing while you're learning the notes. The muscles and ligaments will stretch just like playing a guitar.

The British Shop is were I bought mine several years ago for about $70.00.

I don't see much need for spending the extra money on a blackwood and ivory practice chanter, I'd save that money for a really nice set of pipes. And with plastic, you can pick it up and pllay without the pitch changing based on the moisture of the wood. You only adjust the reed while practicing.

The College of Piping has a great if not the best series of instructional material, I've also got some music from a book called "Privy Piping" which keeps it interesting when you want to try a more modern song.