I have worn hearos on long rides, they are cheap and have worked well when I go to concerts.
On the other hand, ever consider a different windshield? I have Oneal Tirade bluetooth helmet. I set it up to a low, comfortable level of sound before I ride. When I went above 55mph, I could not hear it. I cranked up the volume a little to where I could hear, when I came to a stop, it was uncomfortably loud. Moral of the story- the bike puts out a large amount of noise at speed.
I put on a large cal sci windshield. Noise is a lot less, I can still listen to helmet at low volumes. Rather than buy earplugs, maybe it is better to put money into a windshield that reduces noise?