You can check on the Copanhagan solar oven . It sells for about $ 33.00 dollars OR make it yourself for about $10.oo .
You can Make a Larger version of this Solar Oven , for what ever your needs are .
The reflectors sell at IKEA furnature store for around $2.oo or less , each .
Keep checking on the net for cheap solar ovens ...
Look at the ones available... And build your own , just like the expensive ones.
If you can't build it by yourself , ask a friend to help , and build 2 . Good luck, S-7