Actually Henry Selmer Paris (which is the company that makes the horns as opposed to Conn/Selmer in the US that is olny their distributor but it is an unrelated company with the same name) does quite a bit to protect their name and interests and to warn customers.
I have reported very often the sale of counterfeits and they have acted upon those. They also warn about the fake Selmer instruments on their site.
http://www.selmer.fr/index.php
http://www.selmer.fr/media/FAQ/counterfeit_panpipes.pdf
Unfortunately policing these things efficiently is near impossible and it is not unlike what Louis Vuitton is confronted with ( take a look at this Chinese site clearly offering copies!)
http://www.pursevalley.cn/handbags/louis-vuitton-replicas.php
On the face of it, Amazon and Ebay do have a policy against counterfeits but let's say that they are not particularly scrupulous in enforcing these things. If your items are being faked and the fakes are sold on line by one of these giants it is not that just by complaining ( no matter how big your legal office is) that things are going to be removed overnight ( to reappear under another name minutes after).
http://www.amazon.com/gp/help/customer/display.html/ref=hp_left_sib?ie=UTF8&nodeId=201166010
But, I have said it often enough, the worst thing of all on counterfeiting planet is the counterfeiting of medicinal drugs.
That is a serious threat.
http://www.amazon.com/Fake-items-on-Amazon/forum/Fx2S2JX41LKL663/Tx1FQS00JNGQS7K/1?asin=B000TGB4UU
http://learntogrowwealthonline.com/does-amazon-sell-fake-products-2
Ultimately if you can buy a " Selmer" for little cash anyone knows that they are fakes.
Although with a fake bag or watch you might " pretend" owning the real thing ( but the world knows it because your lifestyle doesn't match the money that the real thing would cost, so what is it that you are pretending?) , by buying a fake Selmer everybody understand that despite the name on it, the thing that you will play is NOT functionally the same ( nor looks, really, the same).
Selmer, like Vuitton ( BMW & Rolls Royce!) have serious problems about this.
Vuitton are sold at every street corner in the world, the police forces of every country could be spending all day long chasing these counterfeits and they don't.
One would think that something serious like cars would be a bit more complex thing to fake and sell, right?
For the time being, the only car market that has opened itself to Chinese copy-cars is the Russian market, despite the fact that the Chinese cars are dangerous look-alike's they say they meet Russian road safety standards ( if there is such thing).
The only defense against fakes is not buying them!
REMEMBER buying a fake is potentially a felony ( it certainly is in the US)