Campmor has the Platypus 2L rig for $18 plus shipping. I picked up 2 and wanted to pass the word. Nothing fancy, but it should get the job done.
http://www.campmor.com/webapp/wcs/stores/servlet/ProductDisplay?productId=39180621&memberId=12500226
http://www.campmor.com/webapp/wcs/stores/servlet/ProductDisplay?productId=39180621&memberId=12500226