Originally Posted by anabolism

As described just a few posts above yours, and as mentioned in the Wiki, you can buy miles using the Mileage Multiplier option. As far as purchasing miles for cash, it's a lousy value at about 3.2 cents per miles, but as a way to get something of value out of the airline fee credit, it's worth it. You can buy a refundable ticket, or buy a non-refundable ticket for travel more than two weeks away so it is cancelable within 24 hours for a full refund. Once it tickets, there will be a Mileage Multiplier option when viewing the itinerary. Use that to buy miles using the AmEx card. Right afterwards, cancel the itinerary. The distance of the trip seems to influence the number of miles offered via Mileage Multiplier.