One of the ways frequent flyer programs make money is to offer their members to purchase miles at various rates. Sometimes there are even bonuses (like the current one offered by American Airlines). It is usually not the best idea to purchase miles for yourself since you will end up paying more for a flight with those miles than if you bought the ticket outright. Additionally, there are usually more direct flights when purchasing with cash (rather than miles) so you get more comfortable options also.
That being said, there are some times when it makes sense to buy miles outright:
- You are almost at the threshold to purchase an award ticket and just need a bit more to get to the requirements. For example, flying to Bali on Korean Airlines is 95,000 miles one-way for their fantastic first class product. If you only had 80,000 miles in your account, you could get that ticket by paying some cash for the 15,000 more miles you need. That would save money on the $18,000+ flight if you bought the ticket in cash.
- When the cost of the miles is less than the approximate value thereof. For example, if the value of AAdvantage miles is 1.7 cents/mile and you can buy them for 1.4 cents/mile, it would make sense to buy them and keep them banked for future use.
- You really really want to take a certain flight and the value of the ticket is worth it for the miles you would buy. For example, if a certain first class flight was $18,000 and to buy the miles would cost only $2,500, then go for it (that is, if you have the money).
Sometimes it makes sense to buy; most of the time it doesn’t. Just keep up with what you have in your account and what upcoming travel you expect to determine your best course of action.