App Santa — last couple days
The App Santa sale is still going on. (I believe it ends the 28th.)
Maybe you got an iTunes gift card?
Vesper, Launch Center Pro, and Day One are just $2.99. 1Password is $9.99. Tweetbot and Clear+ are both $1.99. And there are plenty of other cool apps.
If you want any of these, don’t forget to buy them before they go back to their regular prices.