But I use Etymotic Research IE-6i canal-phones. They are pretty comfortable, and I've worn them for up to 8 hours at a stretch without having them bother my ears too much.
They have great sound quality and have a MSRP of $150, but you can get them for $80 to $90 if you do a froogle.com search.
Do a google search first and read some reviews of them. On the whole, I'm very happy I chose the Etys over Ultimate Ears.
I have two pair of the UE5 Pro earbuds for my ipod video & nano.. I believe the MP3 player is only a fractional cost of MP3 players.. the included earbuds r always inferior.. the ones included w/ipod are worth MAYBE a buck.. /the UE5PRO are good $189-$250/ still not comfortable for sleep.. //anyone know of a reasonable cost custom fit earbud with great sound??