Waste of money unless you are in the professional game.......
Learn the craft properly instead of relying on gadgets.
Semi-agree, I think they can be used before getting to the professional game, but certainly not before level 3. At that level you'll be working with at least semi-competent assistants every game and should be capable of using buzzers.
That said, when I was at L3 I always did 1 in every 4 games without the buzzers to make sure I didn't become reliant on them.