American Airlines is running a sale on the purchase of their miles through November 13, 2015. You can buy up to 125,000 American Airlines miles during the sale and get up to 35,000 bonus miles plus 10% off the normal price.

The discount is fixed, but the bonus miles are tiered, based on how many miles you purchase.

American Airlines miles cost 2.95 cents each plus a 7.5% excise tax, and every purchase has a $30 processing fee.

Through October 23, 2015, United is offering up to a 80% bonus on purchased miles. The size of the bonus depends on the number of miles you buy, with the largest 80% bonus kicking in at 30,000 miles purchased (54,000 total miles after the bonus.)

United miles normally cost 3.5 cents per mile plus a 7.5% tax, bringing the full price to 3.76 cents each.

Avianca LifeMiles and InsideFlyer are offering a 150% bonus on purchased miles through October 12, 2015. You must buy 100,000 to 150,000 LifeMiles (pre-bonus) during the sale at a minimum cost of $3,300.

LifeMiles cost 3.3 cents each, so with a 150% bonus, you get the miles for 1.32 cents each. For instance, if you purchase 100,000 LifeMiles with a 150,000 mile bonus for 250,000 total miles, it would cost $3,300 or 1.32 cents each. That’s the cheapest I’ve seen LifeMiles sold.

Through September 30, 2015, United is offering up to a 75% bonus on purchased miles. The size of the bonus depends on the number of miles you buy, with the largest 75% bonus kicking in at 40,000 miles purchased (70,000 total miles after the bonus.)

United miles normally cost 3.5 cents per mile plus a 7.5% tax, bringing the full price to 3.76 cents each.

Through September 30, 2015, United is offering up to a 75% bonus on purchased miles. The size of the bonus depends on the number of miles you buy, with the largest 75% bonus kicking in at 40,000 miles purchased (70,000 total miles after the bonus.)

United miles normally cost 3.5 cents per mile plus a 7.5% tax, bringing the full price to 3.76 cents each.

Update: Registration for the extra 10% bonus has ended, so all that remains is the normal sale until September 30, which I detail below.

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Avianca LifeMiles is offering a bonus of up to 135% on purchased miles through September 30, 2015. You can buy up to 150,000 LifeMiles during the sale and get up to 202,500 bonus miles.

LifeMiles cost 3.3 cents each, so with a 135% bonus, you get the miles for 1.40 cents each. For instance, 237,350 total miles would be $3,333 or 1.40 cents each.

Update: Registration for the extra 10% bonus has ended, so all that remains is the normal sale until September 30, which I detail below.

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Avianca LifeMiles is offering a bonus of up to 135% on purchased miles through September 30, 2015. You can buy up to 150,000 LifeMiles during the sale and get up to 202,500 bonus miles.

LifeMiles cost 3.3 cents each, so with a 135% bonus, you get the miles for 1.40 cents each. For instance, 237,350 total miles would be $3,333 or 1.40 cents each.

This 75k Hilton offer has expired. Check out the best current travel credit card sign up offers here.

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Today (August 31, 2015 until 11:59 PM ET) is the last day to buy Hilton HHonors points with an 80% bonus.

Hilton points normally cost 1 cent each. With the 80% bonus, the price drops to 0.56 cents per point.

If you buy the maximum 80,000 Hilton points today, you’ll receive 144,000 points for $800.

Until October 6, 2015, you can buy 56,000 or more Alaska Airlines miles for 2.11 cents each.

The sale is structured as a bonus on the normal number of miles you’d receive. The bonus is tiered, so the biggest 40% bonus comes from purchasing 40,000 miles at the normal price of about 2.96 cents each after tax.

To buy 56,000 miles (40,000 + 16,000 bonus) during this sale costs $1,182.50, which is 2.11 cents per mile. This is not the best sale we've seen.

Until August 31, 2015, United is selling miles up to 50% off.

The exact maximum discount is targeted, so you have to sign in to see your discount. My maximum discount is 50%. Even if you get the 50% discount, it only applies to purchases of at least 50,000 miles. United miles normally cost 3.76 cents each, so with a 50% discount, they cost 1.88 cents each.

After the 50% discount, 50,000 miles cost $941.