It's the kind of question that would drive 1L law students crazy; was your response an acceptance or did you condition the sale on her accepting the Hard Rock Dice? If the latter there was no contract. However, even if it was an unconditional acceptance did it get there before she accepted a higher bid? If I taught contracts, which I don't, I might use the case in class or in a final exam. However, in your case I suspect that even if you said yes and sent a $50 MO before she responded you would not have seen the dice.