The consideration would be your promise to pay said funds
The email confirmation is the acceptance
Why would you think there's no consideration?
My reasoning may be incorrect, but I would deem your offer to pay, as simply that, an offer to pay funds and that this alone will not necessarily amount to consideration.
The automatically generated order confirmation email would not serve as contractual acceptance due to what I referenced in the post above and therefore the no valid consideration exists until that point in time. Of course you can view them independently and a promise to pays may in theory be viewed as consideration under certain circumstances but not in this case.
Happy to be contradicted and corrected by someone in the know though. Ultimately though, I was more trying to dismiss the suggestion of threatened legal action.