There is probably something to be said for not spending too much on a whistle until you know the type of whistle and style of music you intend to play.

Get yourself a Cillian O'Briain improved or a Timothy Potter as a reliable not too shrill option (or a Generation or Oak as far as I am concerned, or spend a tenner on an old Feadóg, but you'll have to be able to handle them, they may or may not be 'beginner's' whistles in the usual sense). Once you can handle those well enough, make an informed decision about the aesthetic of the music you want to play and choose a whistle to match that.

The Potter is a quiet well balanced whistle that requires a light touch which makes it ideal for practice, It's perhaps not a whistle you'd take to play out but it does what it does well without upsetting anybody nearby.