I recently went on a bit of a vision quest to find better earplugs. I use earplugs while on the bike, while sleeping, and while using power tools in the shop. I bought every plug at WalMart (look in the sleep aids aisle, the tools aisle, and the sporting goods aisle), I ordered some online, I went bonkers. I tried expensive ones and cheap ones. There aren't really many manufacturers of earplugs, there is a lot of rebranding though.
My results are as follows:
The most comfortable, and most noise blocking (NRR33, 32dB reduction) buds also happen to be some of the cheapest I found, MOLDEX 6800's. These can be had for under $7 for 25 pairs on ebay. I cannot recommend them enough, each wears for me for 3 nights w/ no problem. These earbuds are extremely soft but also large, so the noise blocking is AMAZING while still being very comfortable. Here's a link to what I'm talking about. This is 10 pairs for $4.75
The easiest to find/comfortable are the green "Comfort" ear plugs from the WalMart sleeping aisle. These are like ~$5. They're OK but only about 70% as comfortable as the Moldex and they do NOT block nearly as much sound. They're also finnicky to get in.
My favorite MOTORCYCLE pair are a set of NoNoise Motorsport filtered plugs I picked up on Amazon for like $20. They're only like 25dB reduction, but they're FILTERED, which means that music from the Sena, voices, horns, that sort of thing are perfectly audible while wind and motor noise are largely unnoticeable. They also come in a nice little aluminum, crush-proof tube that fits perfectly into one of the slots in my backpack.
Link to the nonoise motorsport plugs.