I'd day that it's unlikely that a Power Seller would rip someone off on purpose.
However, I've seen the packaging for these fakes.
The boxes and packs look very good.
I don't know if I could tell them apart from the real thing myself!
I'd recommend either buying singles or boxes online.
You can see the single ahead of time, and the box should have a Pokeball imprint on it.
I'll scan what that looks like and add it to the article.
If the Pokeball is not on the shrinkwrap, the box is a fake.
Don't buy loose packs onliine for two reasons:
1. You can't tell if they're fake until after they are opened
2. They could be "scaled", where the heavier packs wtih the holo cards have been sorted out and removed.