Thanks to Kim for this Frugal Baby Tip!
I will be using a diaper service when my baby is born and they actually recommended using a Diaper Champ for the prefolds (with a wet bag/diaper tote on the inside).
You can make your own liner from either 1 or 2 mil PUL or ProCare (which I have never used, but have heard awesome things about!). ProCare is synthetic just like PUL is. I wouldn't recommend using any fabrics besides MAYBE wool lined w/a couple layers of flannel, terry or hemp material????
Even if that works, I don't know how well it will contain smell and it would probably be a pain to wash since you'd have to wash it like a wool diaper cover. You may also run into problems since the wool will be lined with another material and they have different methods of washing. Maybe you could do a wool bag and a separate insert????? Sounds like quite a pain in my opinion, if it even works! Maybe somebody else could shed some light on this?
To help with the smell, you could use Pail Powder or Pail Pals. Another thing I would recommend is just dropping a few drops of Tea Tree Oil on a piece of flannel or fleece in the diaper bag.