Polycarbonate is not the same as plexiglass. Two different polymers. Both bend more than glass, so you would need similar thickness, not thinner (the material you linked to is only 1/8 inch thick - about 3 mm.) Most glass tables I've seen are more like 3/8 inch (10 mm) or 1/2 inch (12 mm).

Have you looked on craigslist for glass you could repurpose? I've picked up glass shelves and glass table tops for free on there before for other projects.

Also, if the price you were concerned about is from a furniture store, try calling a local glass company - they can cut a piece of glass to size for you and its not very expensive. You don't want a sharp edge - for a small charge, they can grind or grind & polish it to make it safe.