A few days ago I decided to double the cost of Pegasus (which I am going to do later today).
Before I did that I emailed my list with the news that prices were going up soon and that it was the last chance to get in on the early-access discount. In the four days between the email going out and the price hike I made 5 sales! That number represents more than 30% of my all-time total.
Creating a sense of urgency really works!
Some more details in my monthly retro: http://www.coryzue.com/writing/aug-2019/