Thanks for finding that link, I couldn't remember the name of the company offhand. I would skip the Avery sound ones if the eargels will do. You can get the eargels for $10 shipped off amazon and it's worth trying them before you shell out $80 for the custom one, unless money is no object.
In which case try both and let us know if the Avery ones are really that amazing...I'm curious.
The important thing about the eargels with the icon is that they say to put the small plain jawbone ring on first. I tried that but since I use the large eargel, I ended up using the large jawbone ring and it holds the eargel very snug, allowing the sensor to rest comfortably on your face. It takes a bit of time to figure it all out the first time you put it together, but so far it seems to stay put really well. Some people say the eargels don't work at all; I think they may be forgetting that you have to put one of the jawbone rings on first, or the eargel has nothing to grab on to.