Why shouldn't they be more than 2,33 ref? It's not a fact that a key is 2,33 ref. During Halloween it was impossible to find keys at 2,33, it was even hard to find them at 2,44. Prices have gone up, perhaps they'll come down in a while when there are more keys in the market again. But as long as people are willing to pay more than 2,33, it's going to be hard to find one for that price.
Edit: Don't take this as I'm saying you should pay more than 2,33 ref, I'm not. I'm just wondering why should keys be exactly 2,33 ref.