Or they could not be. In these days of computer aided design, 3D measurement devices, laser cutting, etc. it is extremely easy to duplicate something.

I've seen a few of these and flown a couple. They aren't too bad considering the low cost. They are not the real thing though and you'll give up a little in hardware, instructions, support and possibly quality in some cases.

If you can accept that possibility and make up for it then you will likely end up with a fun airplane for a great price.

If it does turn out to be an absolute fake then you also have to decide if you are willing to support people who are stealing designs from their legitimate owner. I personally choose not to do that although it is tempting at times.