How to do to realize a full functional BIG touchscreen Ipad?

Hello to everybody, my problem start from the need of realizing a big 42' or greater touchscreen that it is exactly
like an ipad.
This trick has been realized from crunchylogistics.com but as you can see it costs like a car, supercar on big
screens.
So, since I know as you can imagine that really there are not more than 1/10 of real value, WHO can help me in
realizing a similar thing?
At Crunchy they say that no jailbreak has been necessary, they use a pc touchscreen with the ipad but we don't
know how they are connected.
Ipad with a video cable on tv let me see another display, but I want to touch in the big display exactly as what I
see on ipad, I imagine will be necessary at least a program as interface from the two computers, but HOW TO DO?