I hope it's ok, that I give you some advice.
I would buy fan cards right off the market and not buy packs in this phase of your journey.
Every price under 75 SB/Fan is acceptable because even with hundreds of packs a day, you won't beat these rates.
I mostly buy packs now, because it is nice to draw the odd legendary and epics, but if I wanted to be more efficient, I would execute my former strategy, when I was a minnow/dolphin in the game.

Keep having an awesome Rising Star journey.

!PIZZA