I bought a pair of earplugs in an airport shop in Amsterdam recently (the shop with all the weird electronic gadgets). The plugs come in a small pouch and have two differet sets of 'pins' to them. These plugs are made of soft rubber (silicone maybe?) and wearing them for 8 hours hasn't hurt my ears yet. The aforementioned 'pins' have a small hole in them meaning that some sound does go through. The great advantage of this is that although all noises are blocked, pink noise seem to get blocked more, so on the flight deck, I hear the voice and tones more clearly than without wearing the plugs. Don't know about the legal issues, since they are not TSOd, obviously.
They are about 5-8 EUR a set, depending where you buy them.