No, it says zero there, but even with more than 10 S, I can't buy the second one either ;)
Hmm, okay. I'll look into it.
Maybe the problem was right there on the screen—I must have selected 10x or 100x; it works fine at max. Mea Culpa
Oh, haha, that's fine then. I'll check if I can find any bugs still in the game while I focus on the next content update.