Well, not really secret, but these lovelies are not in any of the catalogs so you will only see them when shopping on-line :)
Once upon a time (like, a year ago), Stampin' Up! was testing out the photopolymer market by releasing a new stamp set once a month. And the sets were to be only available while supplies lasted. Then, when the new Annual Catalog came out this June, they stopped releasing monthly sets. But they either had a bigger supply than I thought, or they are still making them! There are 18 of those sets still available, and I just stumbled across this fact the other day. Just look at all of these beauties!
Now, don't you want to do a little shopping? And, bonus! Stampin' Up! is having a sale on ALL of their stamps- 15% off!