Saving them up to buy something "big."
The first 9 I bought I used towards the "Thatsa Bowl." The large one is/was on sale for $10.79 (normally $17.99?). With the 15% off and the shipping added in, it came to $11.66, I think. So I paid an additional $2.66 after cashing in all my eCerts. I could have waited until I had more eCerts to pay for the whole thing, but I didn't want to. I currently have $6 in eCerts waiting to be used for something.