Buying miles is generally for speculative use because the cost to buy usually exceeds the redemption value. However, it can be a smart move in specific, high-value scenarios. When It’s Worth It
: Only consider buying during sales offering 80% to 100%+ bonuses , which brings the cost per mile closer to its actual value.
: Last-minute cash fares are often sky-high, but "saver" award seats (if available) may stay at a fixed, lower mile price. When to Avoid It Are discounted miles worth buying? - Facebook
: If you are just a few thousand miles short of a "free" flight or a major upgrade, buying the difference is often cheaper than paying the full cash fare.
: Buying miles can be worth it for International Business or First Class seats. If a $7,000 flight costs 150,000 miles, and those miles cost $3,500 to buy, you save $3,500.