Okay, so the limited to 5 purchases Energy supply costs 50 gems for 60+40 energy.
I made my first purchase. After which, the price increased to 100 gems for 60+40 energy. That works out to be 1 energy per 1 gem, which is essentially the same as the first one, which is 25 energy for 25 gems.
Obviously, it doesn't make sense to me because... then there's no promotion. In fact, if it weren't for the 40 bonus energy, it'd be 100 gems for 60 energy.. which strikes me as nothing as but a bug.
Anyone care to enlighten?