Consider looking at a Delta-linked credit card that gives you miles with purchases. Use it as a debit card and pay the purchases every pay period. Self discipline has to be exercised so you don't get into debt! Use it strictly to accrue free miles. Then, purchase your upgrade with your miles. I did that with United Airlines because they offered 10,000 miles for signing up for their credit card. I used the card in the same exact manner I just described, and I got the flight for my hunting trip to Spain for free, just with my miles. I also used my miles to significantly offset my upgrade to Africa. Just don't go int debt with it.