Well, looking at the game on DMM right now there's campaigns for:
3 Premium Draws + 2 guaranteed 5* (990 points)
11 Premium Draws + one of any older 5* or 6* you want + other little extras (5000 points)

And I know there've been many other similar campaigns in the past too.

We can only hope that Nutaku will have stuff like these. Buying Flower Stones straight-up really is a complete ripoff.