This reminds me of s.th.
There was a old guy down in my town who was collecting & buying Kinder Surprise toys.
But you didn't got a toy within every kinder suripse.
So, I had a friend who had a very nice trick

In the TV ads it said "Get a toy from every 7th egg" - I didn't heard that particular part consciously before.
So, what we did was, we made a hole with our finger in the bottom to see which package the toy has, as the one's with a "toy figure" were a little bit different most of the times.
Then, when you found one, just count 7 next & get them all. This way we always got the toy's & sold them to him
Talking about BlackHat Business from small ages
Thought, in class 2/3 in every break the pokemon market place opened. It was a little bit like the stock market on the wall street.