I live near Industrial Plastic Supply in Anaheim, California. I buy a variety of plastics from them for various projects. They are only a few minutes away, so I just drive there and buy what I need. If I walk in, there are no shipping costs, and I can talk with an expert about which plastics match my needs. This is a commercial place that caters to contractors, construction people, labs, etc. They are nice to non-experts like me, too. They don't have a fancy showroom, just a typical commercial order desk with a big warehouse behind it, full of different plastic items.
Industrial Plastic Supply, Inc. Anaheim, CA -High Performance Plastic sheet and rod specialists since 1975, Call Us Today 866-832-9315
iplasticsupply.com
-> I wonder if you live near a similar commercial plastics supply source?
Off topic - Here are a couple non-penturning projects where I bought plastic from them:
* Someone in our family had a condo with exposed stairs and balcony over the living room. The metal rail had wide gaps where a baby could fall through. I bought acrylic sheets and attached them to the rail to prevent injury. The plastic was so clear that you could not see it from below.
* I bought plastic sheets, 1/4 inch square plastic rod and special cement. I cut them to shape and cemented the rod around three sides. I put them under our washer/dryer and refrigerator with the open end facing forward. If one of the appliances leaks, the water will be contained and drain out the front where we will detect it, rather than allowing it to pool unseen behind the appliance and damage the flooring.