I have a Rio Nitrus. It has a 1.5 gig drive and a battery life of about 16 hours or so. I have used it on some long rides and have never run out of music. It's pretty user friendly and the prices have dropped. I think you can get them for less than $150. It is 3 x 2.4 x .6 and weighs 2.75 ounces.
The feature I like is "play by genre". When you load the music, you can choose between "rock, blues, standards, jazz, etc.". And you can enter your own genre. I have a genre set up called "cycling". Then it only plays the songs that I have loaded just for my biking. Music really motivates and entertains me. It has been a great addition to my cycling enjoyment.
I usually use only one ear bud when I'm riding, and I don't have the music blasting. I do want to be able to hear that big truck coming to run me over.
Oh... and by the way... I do own the Crusty Demons of Dirt video!