Another sticker chart

It began with a meltdown at Kroger this week. Warner found two of the Disney/Pixar cars he wants for his collection - Snot Rod and Wingo - while we were grocery shopping. They were $6 each, and besides the fact that I was not willing to add $12 to our grocery bill, I thought this could be a teachable moment for our son.

I was about three seconds into my "you can't have everything you want" speech when he started crying. By the time we got to the checkout lane, he was screaming. At one point he was lying face down near the poor kid bagging our groceries, kicking his legs and flailing his arms. I couldn't make this up if I tried. I was so upset and embarrassed, between hissing "Warner, stop right now or I will ... (enter any number of threats you can imagine)" I kept looking around the store desperately, hoping no one was watching us, and wishing the dang cashier would hurry up with our order.

We made it home. And then Warner had the audacity to ask for Snot Rod and Wingo again that night, and the following morning. So, Kevin and I came up with a plan.
We bought Snot Rod, Wingo, DJ, and Boost. They are sitting on top of our refrigerator at this moment, waiting to be "earned". We have a new sticker chart on the fridge, with each of the cars listed on it. Warner earns one sticker for something Kevin or I decide (for instance, getting through Target without throwing a fit or staying in his room until 7am in the morning). Once he has five stickers, he gets one of the cars. He can also earn money for his piggy bank and pay us $.25 for one of the cars.

So far he has three stickers on his chart. Is this bribery, or a lesson we're teaching? I'm not sure. Where is the manual on parenting when you need it?