I've seen a variety of products out there and most companies are producing a really nice product for Windscreens.
I've recently taken on a new philosophy - SHOP LOCAL and it paid off in spades.
I made a pattern for a windscreen and submitted to my local glass place.
They suggested not plexi but LEXAN. It's much less scratch resistant and will not fade yellow with the UV sun rays.
Cost $20/sq ft - 42" wide, 12" tall = $70.00 cut and shaped... Not bad...
Nothing fancy but perfect to reshape the backdraft....

Local food for thought...
Droid