Hello,
It's not purely luck; some ninjas have harder skillbreaks because they are more valuable ninjas. Fusion Kisame is one such ninja. Most players report his skillbreak taking between 600 and 1000 vials to complete. This is not a bug. This is intended. He is a very powerful and versatile ninja, and his full skillbreak is not intended to be cheap or easy to get.

As for skillbreaking materials, it is not a bug that you cannot find these materials in the grocery shop. They have not been released there yet.

Hope this information helps, thanks!