Efrem -- Depending on the FF program you're on, you probably want to check to see if their in-flight mail-order catalog includes a fitness store. Either that, or maybe a Sharper Image or Hammacher Schlemmer type place. I know at least with United, they had some special promotion going where you earned extra miles if you shopped from their SkyMall catalog last year.

Obviously, putting it on your FF credit card will help, too.

The biggest problem would probably be in purchasing a treadmill that you haven't tested. I'd be leery of making such a purchase; it's one thing to have use a treadmill for a few workouts at the hotel gym, and another to own one that serves as your primary workout machine. You might want to look at past issues of Consumer Reports to see which models they recommend. [Actually, I think their January '05 issue is a fitness issue that includes a list of recommended dreadmills.]