Continuing a Birthday Gift Tradition

We have a long tradition of buying the girls ridiculous birthday presents. One year they received a dog. Another year they received a playset. This year they received iPhones.
I know. I know. It's a crazy, expensive birthday present. The stars aligned so that their old devices didn't work any more at the same time as our contract was up for renewal. When they started negotiating for an iPhone, we set some hard terms. One term was that this was their birthday present. Sure, their existing devices were broken and unusable. Of course we were going to need new devices. iPhones, though? Before those came into the house we set out some tough terms.
One item negotiated was that the girls would sit through the entire process. They had to stay with Daddy while he finalized the contract. They had to sit while the representative transferred data from the old devices to the new iPhones. They wanted the iPhones so badly that they would have done anything. We should have negotiated harder.
They came home deliriously happy. They couldn't believe that we really bought them iPhones. When I looked at the invoice, I couldn't either.