I've seen that before, and even if it does work, I would not buy one.
Look at how many oddly moving(un-lubricated) parts are inside that engine.
A regular steam piston engine is very reliable.
Even a make-shift steam turbine made from an Automotive Turbocharger is extremely reliable.
I'm not sure how long a machine like this would last, if it even does produce useful mechanical power.
Personally, I have plans to build a Solar Thermal collector (in a trough design) and it will feed 300+ degrees F steam into an automotive turbocharger (a cheap turbine) that will turn automotive alternators to generate electric power.
The poor-man's steam power.
This system will also take the waste steam from the turbine and condense it back into hot-water(via automotive radiators for condensers) to supply hot-water to the house.
Or be routed into a steam-fed indoor radiator system to heat the house in winter.
I plan to have 100+ square feet of solar troughs to collect a massive amount of heat from the sun, using cheap(and replaceable) Mylar Flexible mirror.
This system can also provide distilled fresh drinking water or
Refrigeration(and air conditioning) via an absorption refrigerator (a heat powered refrigerator, like propane-powered ones in RVs)
If you want to see more, check out http://www.solarturbinegroup.org/
They're already doing it in South Africa.
If they can do it, why can't I?