From now till December 27, 2016, Freshmen (formerly known as Kinky Angels) is offering a $10 off on their monthly membership until cancelled. This is the same price offered for members of Belami Online to join Freshmen.
Helix Studios is offering their members 30% (or is it 43%?) for 1 month of membership. If you can wait, there is a bigger discount on the 23rd to 26th of this month.