If you buy it new it sets you back $25-$30.
Thift stores sell them for cheap but clean it out
with bleach and water.
But beware refils cost alot.
Wal-mart selles them for $14.99 and up.
And then there is also the Diaper Camp.
Uses ordinary plastic garbage bags.
It might be hard finding it in a thrift store but to buy it you can go through ebay,target or babies r'us.