You can make 100% of the consumables for the ZCorp Printers. We had a 510 Spectrum and made our own binder from bulk grocery items and used powders in bulk from a different application that also was dirt cheap.
We even went so far as to find out the main components of a popular casting powder and started buying the components for that in bulk. If you are willing to do some digging, running these machines can be extremely cheap, other than going through the print heads. Luckily those too can be sourced for cheap(er).
We have found having quality 3D scanning technology has been more helpful than the printer was. As others have mentioned, the Z-Corp powder printing is useful for a few types of printing, but the parts are far from actually useful for prototypes.
Regards,
Dave @ NervIndustries