I use E.A.R.
A few quid for a pack of 20, individually packed in pairs. Excellent and cheap.
I don't use them on the bike, only in shops, cafés, pubs etc. especially for Xmas carols.
Have them in almost all day these days as a local arty-farty site has an enormous extractor on their roof. It's making me ill. Seems to come off every wall, often all day, sometimes all night as well. Even with some Bilsom defenders on top, the humming still grinds in the skull.