Columbine (briefly) 55% off at Amazon
To be honest, I have no idea who sets the discount there, or how or why or when. So I have no idea how long the sale will last.
(It's typically about $12 or more online. The cover price is $17, which you pay at most physical stores.)
So order while they last: Columbine at Amazon.
Update Aug 16: It was 50% off when I posted this, but it dropped to 62% off. I updated above.