You can order them directly from shop.lego.com and save on shipping (and tax).
I personally do not like this particular gyro. It is a single axis analogue sensor that is affected by drops in voltage level (when you start a motor for example). You should also consider the IMU sensors from Mindsensors and Dexter Industries. They pack a much better sensor ( 3-axis + 2-axis accelerometer) for about the same price.
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