A scary thought from Ellery911

I've thought about this for a long time and being a newbie to high end I just had to ask.

In a world where you can get fake Luis Vuitton bags, fake high $ watches (Rolex, Patek Phillipe etc), and knock-offs of just about any high $ product, have there been any instances of fake high end stereo equipment and if so, how does one avoid being the unlucky buyer?