I'm doubtfull that those things at the bank are plexiglass, probably something a lot tougher. But then they may not really be bulletproof, just something to prevent a bg from entering. I haven't asked at a bank, and doubt that they would tell me if I did.

Plexiglass from a home store, in my guesstimation, would not be all that bullet proof. It can get stress cracks pretty easily. Stuff scratches badly too, and will become cloudy unless you clean it with the proper stuff...