I don't want the bluntness of my advice to obscure the kindness with which I offer it: Buying miles at $0.02 to $0.025 each, and then keeping them for almost 15 years, is an awful idea. Airline programs see steady devaluations spaced not more than a few years apart, and there's no end in sight for this trend. Save your money, invest it for 15 years. Double or triple it. If you put it in miles, it's going to be worth a fraction of what you paid.

Buy miles at that rate only to top off your account for immediate redemptions.