Solar Powered Gadgets do NOT have to be expensive

I have this post from the British Telegraph newspaper which describes an invention that has been widely talked about in the media over here, though I have not seen it reported in any Indian newspaper yet: http://www.telegraph.co.uk/earth/earthnews/5128004/Cardboard-cooker-wins-global-climate-change-competition.html I think that the design of a cheap solar heater to boil water to purify it could just as easily be used to cook rice or boil vegetables or meat, for example. I remember similar cookers being sold in Chennai at the Chintamani Co-operative stores some decades in the past but am not sure if they are still sold there. In any case, the UP and Haryana state governments make and sell solar cookers which cost a lot more. Perhaps, there is time for someone to look at making cheap ones and selling them? No need to worry about gas cylinder delivery delays, kerosene, etc . . . Hope this opportunity for entrepreneurs finds a sympathetic ear here!