Isn't framing with Perspex cheaper than glass? There's a common, public misconception that Perspex, or plastic glass, as most customers call it, is or should be considerably cheaper and more readily available than clear glass. But in fact, the opposite is true. Plastic-based materials such as perspex or acrylite and polyethylene sheets actually cost 3 to 6 times more to buy than than clear picture framing glass sheets, depending on quality. Importantly, these materials aren't as readily available because picture ...