If you were unaware, a recent update to the Valve Store allowed users to display pricing in a localized currency. However, something was lost in translation as 1 euro equaled $1 (USD). Due to the differences in exchange rates and the value of the USD compared to the value of the Euro, it means that Europeans are now paying exceptionally inflated prices for their Steam purchases. There's a rather large Steampowered thread detailing the issue far better than I ever could.

Valve stated that they are aware of the pricing issue with the new Euro currencies in use in the Valve Store: "Yes, we agree that some of the prices for third party products are higher then what you can find locally but we are working to fix that."

As noted though, Valve is aware of the issue and is working on a fix for it.