Many airlines are having sales today. Here's a roundup:
American Airlines: 1.77 Cent Miles
American Airlines is offering up to 120,000 bonus miles for miles purchases made by Monday November 27, 2017. If you buy the largest amount possible, you can get the miles for as little as 1.77 cents each. We saw them on sale for 1.72 cents in July, so this isn't even the best deal of the year.

Bonus miles are tiered based on how many miles you purchase.

I've been hopping around Europe for the last few months with flight that I've booked a variety of ways:

Barcelona, Spain to Leipzig, Germany (cash, Vueling)
Prague, Czech Republic to Belgrade, Serbia (Etihad Guest miles, Air Serbia, Anatomy of an Award)
Belgrade to Tivat, Montenegro (cash, Air Serbia)
Sarajevo, Bosnia to Zagreb, Croatia (cash, Croatia Airlines)

Now I have two more flights coming up from Zagreb to Spain and back for a quick trip.