I meant to mention, I found the blind bags up front right on the Customer Service/Returns counter by the cashier, not in the pony aisle. So make sure to check everywhere for them if you don't find them. The sticker wasn't marked with the sale price, but the sale did work when they were actually rung through. The cashier watched me pick through the box checking codes on my iPhone and only after I'd paid did she finally ask what I had been doing. When I showed her the codes on the bags she thought that was fantastic!
I did think it was very interesting that the MLP blind bags were up front where they could be watched but the LPS ones were in the aisle with the LPS, right beside the ponies.