The fleece tunnels are wonderful for when you are using fleece bedding. When used with shavings they tend to get hard to clean. My pigs on fleece love their fleece tunnels from Jen.
I buy the cardboard tunnels from Drs. Foster & Smith online. They often have sales where the price is less if you buy a certain amount. They often have free shipping, too. I usually give my new adopters one (or a washed, used pigloo, or both!). I just throw the yellow fluff away, or use it as batting in pillows.
I love the cardboard tubes (also called Chubes, or Chewbular tubes). The pigs don't get trapped inside by other pigs, and they don't get all hot and sweaty (pigloos can be little ovens). Some pigs will chew them up pretty fast, while others don't even chew them at all! Some pigs get them pretty messy with poop and pee, so you may have to throw it out if it gets too gunky.
(I apologize for bringing up an older thread--but I was just discussing this topic with an adopter the other day!)