If you really wanted to compare buying miles....If you went to Delta's site and bought 15,000 miles (which is the most that you could add to one account) you would pay $412.50 at the going price of $.0275 cents a mile, add the 7.5% excise tax and the $25 handling fee and you have a grand total of $468.43 or just over 3 cents a mile.

On the other hand, if you purchased 5 subscriptions to InsideFlyer for your 15,000 miles - cost of $299.75 you are at 2 cents a mile....I would certainly choose InsideFlyer!

........and of course both ways allow the double miles if you are using your Delta AMEX card as a form of payment.......