American Airlines has increased the bonus on the purchase of AAdvantage miles through January 4, 2016. You can now buy up to 150,000 American Airlines miles and get up to 115,000 bonus miles, for a total of 265,000 miles, for 1.81 cents each.

The bonus miles are tiered, based on how many miles you purchase. There is a new bonus of 115,000 miles for buying 150,000.

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

Update: Below is my bonus offer. This is a targeted bonus, so yours may be different.

Through December 18, 2015, United is offering a 100% bonus on purchased miles. The size of the bonus depends on the number of miles you buy, with the largest 100% bonus kicking in at 30,000 miles purchased.

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 Passageiro de Primeira are offering a 150% bonus on purchased miles through December 15, 2015. The minimum purchase is only $66.

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 10,000 LifeMiles with a 15,000 mile bonus for 25,000 total miles, it would cost $330 or 1.32 cents each.

Through Friday December 4, 2015, British Airways is offering a 40% bonus on the purchase of Avios. The biggest bonus ever offered on the purchase of Avios was 50% in February, so this is a big bonus.

The maximum Avios you can purchase in a year is 35,000. With a 40% bonus, that means you can add 49,000 Avios to your account.

Ending today (Monday November 30), Avianca LifeMiles is offering a bonus of 140% on purchased miles. You can buy up to 375,000 LifeMiles during the sale.

LifeMiles cost 3.3 cents each, so with a 140% bonus, you get the miles for 1.375 cents each. For instance, 4,800 total miles would be $66 or 1.375 cents each.

This is the cheapest I have ever seen LifeMiles, and slightly cheaper than the 1.4 cents each that they cost last week.

More importantly, most LifeMiles sales require a huge purchase (last time $3,333+) to get the lowest price.

Until December 31, 2015, you can up to 20,000 Starpoints with up to a 25% discount on the normal purchase price.

Starpoints are normally sold in increments of 500 points for 3.5 cents per point.

Last week I posted that LifeMiles were being sold with a 125% bonus, bringing the price down to 1.47 cents per mile. In the past I have purchased LifeMiles when the price dipped to 1.5 cents or less because that allows for a one way ticket in Business Class to Europe for about $1,000.

If you are an InsideFlyer member (free sign up), you can get an extra 10% bonus on your purchase, bringing the price of purchasing 92,250+ miles down to 1.47 cents per mile and purchasing 237,750+ miles down to 1.40 cents each.

Avianca LifeMiles is offering a bonus of up to 125% on purchased miles through December 18, 2015. You can buy up to 150,000 LifeMiles during the sale and get up to 187,500 bonus miles.

LifeMiles cost 3.3 cents each, so with a 125% bonus, you get the miles for 1.47 cents each.

Alaska Airlines' newest miles sale offers miles as cheap as 1.97 cents each, which means Emirates First Class from the United States to Dubai for around $1,800 (or anywhere else in the world for around $2,000) or Cathay Pacific First and Business Class from the United States to Hong Kong and Johannesburg for around $1,400.

Until December 23, 2015, Alaska is offering an instant mystery bonus on miles purchases of 35% to 50% more miles.

Through December 14, 2015, United is offering up to an 85% bonus on purchased miles. The maximum bonus is targeted with some people being offered 60% and 70% bonuses. Also the size of the bonus depends on the number of miles you buy, with the largest 60%, 70%, or 85% bonus kicking in at 40,000 miles purchased.

Log into your account here to see the bonus you are offered. I was offered the 85% bonus.

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