I've had a good look around and that seems to be about standard everywhere for a 40mm gate. 32mm are considerably cheaper.
I wish I used a gate valve on mine though, the massive 50mm ball valve was job and half setting right. Used to find myself putting tension on the handle, then gently tapping it to knock it in fine increments. I think a gate would be a good investment providing it's the screw type (most seem to be) not the slide type.