Thanks to higmanschmidt for starting this poll! We've contacted the vendor on your behalf and they've made the Etymotic Research ER20 Earplugs available.
I've been using the Etymotic. They're great for what they cost. They do not alter the sound much. The only issue is that their tri-flange tips might not be very comfortable for extended wear. But I guess if you want a good seal, tri-flange is the way to go.
