While 3D printers continue to drop in price, the cost of 3D printing materials hasn’t really changed much in the last few years. That is leading the maker community to start producing DIY filament extruders like the one just uploaded to Instructables by user Cpriolo14. He says that his extruder can be built for less than $200 and can be constructed from easy to find and readily available parts. Further details on how to create this machine can be found in the article here: http://3dprint.com/69727/diy-filament-extruder/
Below is a picture of this DIY filament extruder. As you can see it's rather simple, but Cpriolo14 ensures the community that it does in fact work rather well: