We have a "franchise"-acustic device manufacturer in Germany, called "Kind".
They mainly produce individual hearing devices, but are able to make you some nice ear plugs, too..
I paid app. 200 Euro for mine....and they fit like nothing else.
They use gel to get a negative from your ear, then it takes a week (or so) to get them done.
You can change the "silencer" inside the plugs yourself...
I like them, because they take away a lot of noise-but i am still able to hear the engine (and other "noise") around very clearly....