Take a look on the internet a little and you will find glass companies that specialize in making custom car glass and windshields. I can't imagine that they would be selling all those windshields, on the internet, without them being DOT certified. In any case, a quick search and phone call should give you an idea if it can be done or not as well as a rough $ estimate.
I did this recently so that's how I know about these places, but my windscreen, while made out of glass, did not need to meet DOT requirements.
I did this recently so that's how I know about these places, but my windscreen, while made out of glass, did not need to meet DOT requirements.