Buying one to use in January for $40.
Also can someone confirm that they don't ask for the AMEX card that it is booked under at check in?
When I used the credit (my own), nobody asked to see the card. It's prepaid, so as far as the hotel is concerned, they got their money.
A side benefit is that you can use any card you want for any incidentals/extras charged to the room, since you've already fulfilled the requirement of paying for the stay with an Amex.