Polycarbonate (Lexan/Makrolon) is softer, easier to cut and more crack resistant. The downside of it being easier to work with is that its easier to scratch
Acrylic (Plexiglass) is harder and more scratch resistant, but you have to be more careful cutting and drilling it because it will crack.
Acrylic/Plexi is usually the choice for arcade games because its more durable. Use a piece of scrap wood or something behind it when drilling to prevent that. Maybe practice on a spare piece first to get a feel for it.
Polycarbonate should be fine for home use, but you have to be more careful with it. It will get swirl scratches in it from dust if you clean it with a dry cloth.
Edit to add... I found a local place when I got mine. Just looked up plastics in the Yellowpages. I was buying whole sheets for bezels and overlays when I was building my MAME cabs. Would have been impractical to ship.