Honestly, rigid plastic frames are one place you don't want to cut corners. Unlike flexible TPU frames (the industry standard), rigid plastic doesn't conform to your face, which means uncomfortable pressure points and gaps that let cold air and snow in. The bigger issue is safety: rigid plastic becomes brittle in extreme cold and can actually crack on impact — not what you want protecting your eyes on the mountain.
Rigid frames also make lens swaps nearly impossible since there's no flex to pop lenses in and out. You'll mostly find this material on ultra-budget or rental goggles, and it's easy to see why resorts replace them frequently.
If budget is tight, look for TPU frames instead — they're standard even on affordable goggles from reputable brands and will stay flexible, comfortable, and durable all season. The small savings on rigid plastic isn't worth the discomfort or risk of a cracked frame in cold weather.