Your hearing is probably the most important part of your musical arsenal. It comes free, but if you don't take care of it then you're in trouble.The Lin-Ear PR20 Music Earplug from ProGuard is perfect if your budget can't stretch to £200 for pro ear-defence; it really makes the £15 price tag a bargain.
Despite the generic shape, they are very comfortable and come in two sizes, so there should be something for everyone.
The vented design allows unwanted frequencies to escape for a more natural feeling. And the key ring case means you have no excuse not to wear them.