I have seen those fake Tenergy on Aliexpress. If they are non-tensor, which is probably the case, I would not buy them even at $11. At that price I would rather buy Mercury II or Sanwei TT88 UltraSpin for around $8-9 with import taxes and shipping included.
I like to buy blade clones. For example, I own a couple Stuor Viscaria's. They are actually quite good and of course they say Stuor on the blade's face and blade's handle. After all, the blade composition is not a big industry secret. And I am sure it is not "patentable." Anyone can try to duplicate the wood and carbon composition of the blade and is not infringing on any patent per se.
Out of the three major clone companies coming from China: Stuor, XVT and Lemuria, I like Stuor the best so far. Their blade handles are comfortable. Shipping is very fast. I own a real Viscaria. Stuor's Viscaria clone plays eerily similar. However, does Stuor really use the same carbon material? I assume everyone's ALC's or ZLC's carbons are different, from Stuor to Butterfly to Tibhar to Gambler to Joola. Furthermore, we all know that each patch of wood is different. Even Butterfly's Viscaria from blade to blade, it will play differently. Hence no one can guarantee the weight range of any blade really at the end of the day.
However, I have noticed that some Lemuria blades literally print Viscaria on it or ZJK special edition, with Butterfly logo and name, including on the blade's face and blade's handle. I have a problem with that. I would not buy any blades like that. There is no question at that point they are infringing on logo's, etc. I would not buy and support that.
If I have a Stuor Viscaria clone, then I want my blade to say Stuor, both on the face and the handle. I don't care if they print "Stuor" all over the blade because it is a Stuor blade. Big deal I use a cheap carbon blade.
If have a Lemuria blade that is made by Lemuria but it prints Butterfly and Viscaria all over the blade, then that is going too far.
I don't buy bags. But I have no problem buying a generic bag for cheap and it lasts for a while because it is well made. Great.
But if the bag is fake, being sold by some roadside stand in Hong Kong, for twenty dollars and it says Gucci on it, that's going too far. I would not buy it for the principle of it.
So everyone of us has to figure out what he or she is comfortable it.
Again it is not like other major table tennis brands have not tried to copy Viscaria composition and stamp their own logo on the blade. Of course Viscaria is one of the most popular Butterfly or non-Butterfly blades in history. So anyone, including other major table tennis brands, trying to copy the composition of the blade, that is fair game.
But to copy it and put Butterfly printing and logo's on it, I would never support that at all.
Therefore, going back to the original topic, I would not buy a fake Tenergy no matter it is 5 dollars or 11 dollars. But I would be more than happy to buy Mercury II or Sanwei T88 Ultraspin for cheap.
However if OP did buy a sheet and it is genuine, then I would buy it myself.