FilabotFrom filabot.com :
Filabot is a desktop extruding system, capable of grinding various types of plastics, to make spools of plastic filament for 3D printers. Not only is it user friendly, but it is also environmentally friendly. The Filabot can process things such as: milk jugs, soda bottles, various other types of plastics, and bad prints, to make new filament for a future print. Filabot will bring the real power of sustainability to 3D printing, allowing for a one stop shop to make anything.
Lyman Filament ExtruderFrom http://www.thingiverse.com/thing:30642 :
The Lyman Filament Extruder is a machine that extrudes filament from pellets for use in a 3D Printer. It can extrude 1.75mm and 3mm filament with easy nozzle exchange. The material cost is about $250.On their thingiverse page there are plans, files and guides available.