You can always buy it from your local shops. You can check the product physically before you order it. However, your local shop probably won’t have a lot of variations for the shower door because that’ll require a massive space.
You can order it from online to get a wide variety of colors and variations. The most popular online place to frameless shower doors from is of course Amazon, eBay, Walmart. You can check out the rating and highlighted features, along with elaborate frameless shower door reviews for any particular product.
So if any brand is bluffing, you will know right away! In case you receive any faulty product, the manufacturer will be happy to replace it.